All positive integer solutions to $\frac{1}{x_1}+\frac{1}{x_2}+\cdots+\frac{1}{x_n}+\frac{1}{x_1 x_2 \cdots x_n}=1$
As the title states, how would I go about finding the positive integer solutions of
$$\frac{1}{x_1}+\frac{1}{x_2}+\cdots+\frac{1}{x_n}+\frac{1}{x_1 x_2 \cdots x_n}=1$$?
Thank you for your help.
Edit: I think I've made some progress. I conjecture that you can expand the set {a, a+1, a*(a+1)+1, a*(a+1)(a(a+1)+1)+1, ...} (i.e. multiply all previous solutions and add 1), where a=2, to size n, and that will always be a solution in the case of n variables. This is far from finding all positive integer solutions, though.
Edit 2: For example {2}, {2,3}, {2,3,7}, {2,3,7,43}, {2,3,7,1807}, {2,3,7,43,1807,3263443} are all solutions in the case where $n=$ size of the solution set respectively.
This is known as the improper Znám problem.
All of the solutions for $n\le 7$, as well as an algorithm to compute them are given in Brenton and Hill's 1998 paper. All of the 119 solutions for $n=8$ are reported to have been found in Brenton and Vasiliu's 2002 paper, but the link containing the solutions appears to have decayed. Regenerating the first hundred or so of these solutions is easy, but finishing the last few will probably take a couple of weeks of computer time. Finding all the solutions for $n=9$ looks intractable without a breakthrough in the search techniques.
Brenton, Lawrence; Hill, Richard (1988), "On the Diophantine equation 1=Σ1/ni + 1/Πni and a class of homologically trivial complex surface singularities", Pacific Journal of Mathematics 133 (1): 41–67
Brenton, Lawrence; Vasiliu, Ana (2002), "Znám's problem", Mathematics Magazine 75 (1): 3–11
As the link mentioned in the Mathematics Magazine article is inaccessible, I have rerun the code described in the article, and I report the results (122 octets for $n=8$) here. It appears that the run described in the article missed three of the octets. I assume that the missing octets are the ones mentioned in the OEIS article found by Zhao Hui Du.
2 3 7 43 1807 3263443 10650056950807 113423713055421844361000443
2 3 7 43 1807 3263443 10652778201539 41691378583707695
2 3 7 43 1807 3263443 10699597306267 2300171639909623
2 3 7 43 1807 3263443 10650057792155 134811739261383753719
2 3 7 43 1807 3263447 2130014000915 22684798220467498090185211
2 3 7 43 1807 3263447 2130014387399 11739058070963394487
2 3 7 43 1807 3263479 288182779055 243811701792623
2 3 7 43 1807 3263483 260604226747 80249212735823
2 3 7 43 1807 3263495 200947673239 67137380077902268343
2 3 7 43 1807 3263495 200949404503 23316080984691959
2 3 7 43 1807 3263531 119666789791 8081907028348841339
2 3 7 43 1807 3263591 71480133827 761302020256877140089595
2 3 7 43 1807 3263779 31834629787 4396910340967
2 3 7 43 1807 3264187 14298637519 152316021000302785506427
2 3 7 43 1807 3316627 203509259 109643149191047
2 3 7 43 1807 3586039 36800447 2550097247
2 3 7 43 1811 655519 389313431 1507818475
2 3 7 43 1811 713899 7813583 2409102303622951
2 3 7 43 1811 793595 3722287 233296531681207
2 3 7 43 1817 298637 279594269 3859101523354821017
2 3 7 43 1819 252731 2134319143 6047845668256680791
2 3 7 43 1823 193667 637617223447 406555723635623909338363
2 3 7 43 1823 193667 637617223459 31273517203328870463055
2 3 7 43 1823 193675 4683210919 754794584867
2 3 7 43 1831 132347 231679879 1197240789041771
2 3 7 43 1891 40379 9444811 55866875
2 3 7 43 1943 25615 456729463 450222796871
2 3 7 43 1951 30571 118463 14484098803019
2 3 7 43 2105 12773 2775277 168100338289
2 3 7 43 2137 16921 37501 49708999789
2 3 7 43 2755 5407 172771 357538828973647
2 3 7 43 2813 5045 692705317 188433744928309
2 3 7 43 3263 4051 2558951 61088439723561979
2 3 7 43 3559 3667 33816127 797040720326433787
2 3 7 47 395 779731 607979652631 369639258012703445569531
2 3 7 47 395 779731 607979655287 139119028839856004123
2 3 7 47 395 779731 607979652683 6974325623477705424647
2 3 7 47 395 779731 607979793451 2624887933109395111
2 3 7 47 395 779731 607979652647 21743485766025360000683
2 3 7 47 395 779731 607979697799 8183472856913555659
2 3 7 47 395 779731 607979653531 410254449012081168631
2 3 7 47 395 779731 607982046587 154405744751990423
2 3 7 47 395 779743 46768385339 1672627310178141725483
2 3 7 47 395 779747 35764242947 12154487527525118239
2 3 7 47 395 779827 6286857907 2158880732959
2 3 7 47 395 779831 6020372531 3660733426607933569531
2 3 7 47 395 781727 305967719 125881309327
2 3 7 47 395 782111 257276179 57278664659
2 3 7 47 395 782287 277442411 1701723083
2 3 7 47 395 782611 211810259 1592773460578079
2 3 7 47 395 816247 17428931 652510750371360683
2 3 7 47 395 1108727 2627707 140495574531059
2 3 7 47 403 19403 15435513367 238255072887400163323
2 3 7 47 403 19403 15435513463 2456237880094942747
2 3 7 47 403 19403 15435513395 8215692183434294399
2 3 7 47 403 19403 15435516179 84697872837562655
2 3 7 47 415 8111 6644612311 44150872756848148411
2 3 7 47 415 8111 6644613463 38292177286592827
2 3 7 47 415 8111 6644612339 1522443894582665279
2 3 7 47 415 8111 6644645747 1320426321921983
2 3 7 47 449 4477 12137 34035763385
2 3 7 47 583 1223 1407479767 1980999293106894523
2 3 7 47 583 1223 2202310039 3899834875
2 3 7 47 583 1223 1468268915 33995520959
2 3 7 47 583 1223 1407479807 48317057302587443
2 3 7 53 209 10589 19651 86321
2 3 7 53 269 817 7301713 48932949591475
2 3 7 53 401 409 351691 397617853
2 3 7 55 179 24323 10057317271 101149630679497570171
2 3 7 55 179 24323 10057317467 513449911932648503
2 3 7 55 179 24323 10057317311 2467064172726591731
2 3 7 55 179 24323 10057325347 12523178395739983
2 3 7 55 179 24323 10057317287 5949978284730273323
2 3 7 55 179 24323 10057320619 30202945461748519
2 3 7 55 179 24323 10057317967 145121431390804003
2 3 7 55 179 24323 10057454579 736667018400959
2 3 7 61 187 485 150809 971259409
2 3 7 61 293 457 551 21709309
2 3 7 65 121 6271 1579937 2869621
2 3 7 67 113 28925 48220169 4074021053
2 3 7 67 113 29153 3712777 45401353
2 3 7 67 113 34477 178945 178344158228021
2 3 7 67 187 283 334651 49836124516795
2 3 7 71 103 65059 1101031 4400294969594807
2 3 11 17 79 301 1049 3696653
2 3 11 17 97 151 444161 317361415625
2 3 11 17 101 149 3109 52495396603
2 3 11 23 31 47059 2214502423 4904020979258368507
2 3 11 23 31 47059 2294166883 63772955407
2 3 11 23 31 47059 2215070383 8636647107907
2 3 11 23 31 47059 2214502831 11990273552017987
2 3 11 23 31 47059 2446798471 23325584587
2 3 11 23 31 47059 2214502475 92528699894575367
2 3 11 23 31 47059 2244604355 165128325167
2 3 11 23 31 47059 2214524099 226233749172527
2 3 11 23 31 47059 2214502427 980804197623275639
2 3 11 23 31 47059 2612824727 14526193019
2 3 11 23 31 47059 2217342227 1729101023519
2 3 11 23 31 47059 2214504467 2398056482005535
2 3 11 23 31 47059 3375982667 6436718855
2 3 11 23 31 47059 2214502687 18505741750517011
2 3 11 23 31 47059 2365012087 34797266971
2 3 11 23 31 47059 2214610807 45248521436443
2 3 11 23 31 47063 442938131 980970939025927675
2 3 11 23 31 47063 447473399 43702604167
2 3 11 23 31 47095 59897203 132743972247361531
2 3 11 23 31 47119 36349891 4619150372467
2 3 11 23 31 47131 30382063 67384091875543675
2 3 11 23 31 47147 24928579 11061526082145911
2 3 11 23 31 47243 12017087 26715920281613179
2 3 11 23 31 47423 6114059 13644326865136507
2 3 11 23 31 47479 5307047 2371471764522551
2 3 11 23 31 47491 5161279 4952592862147
2 3 11 23 31 49759 866923 2029951372029307
2 3 11 23 31 60563 211031 601432790177275
2 3 11 23 31 74963 126415 259118345891
2 3 11 23 31 84527 106159 84453127154999
2 3 11 25 29 787 264841 2542873
2 3 11 25 29 1097 2753 144508961851
2 3 11 31 35 67 369067 1770735487291
2 3 13 25 29 67 2981 11294561851
2 5 7 11 17 157 961 4398619