Concatenate two files and separate them with a newline

I have two files:

k.txt:

3 5 7 9 19 20 

h.txt:

000010
100001
111001

if I just use cat, there is no newline. I need a command which would provide a file which looks like this:

3 5 7 9 19 20 
000010
100001
111001

If, as steeldriver suggests, your files don't end with a newline, you could try:

awk '{print}' k.txt h.txt > newfile

or, if you like golfing

awk 1 k.txt h.txt > newfile

or

perl -lne 'print' k.txt h.txt 

or

( cat k.txt ; echo ""; cat h.txt; echo ) > newfile

or

echo "$(cat k.txt)"; echo "$(cat h.txt)"

Try this with bash:

cat k.txt <(echo) h.txt > new.txt

Using sed:

sed '/^/ r h.txt' k.txt

or better (thx @steeldriver)

sed '$a\' k.txt h.txt

Using ed:

(echo "0a"; cat k.txt; echo "."; echo "wq") | ed -s h.txt

and for the missing newline in k.txt:

(echo "0a"; cat k.txt; echo ""; echo "."; echo "wq") | ed -s h.txt

or if you need a separate output file:

(echo "0a"; cat k.txt; echo ""; echo "."; echo "w out.txt"; echo "q") | ed -s h.txt