OFFSET
1,2
COMMENTS
The sequence contains A001710 when x=y.
EXAMPLE
630 is in the sequence because with x=6 and y=7, 6!7!/(6!+7!) = 720*5040/(720+5040)=630.
PROG
(PARI) lista(nn) = select(x->(denominator(x)==1), setbinop((x, y)->x!*y!/(x! + y!), [1..nn])) \\ Michel Marcus, Jun 27 2024
CROSSREFS
KEYWORD
nonn
AUTHOR
Michel Lagneau, Jun 27 2024
STATUS
approved