A374072 - OEIS

%I #16 Jun 28 2024 14:28:05

%S 1,3,12,20,60,360,630,2520,4480,20160,36288,181440,1814400,3326400,

%T 19958400,239500800,444787200,3113510400,5811886080,43589145600,

%U 81729648000,653837184000,1302884352000,10461394944000,19760412672000,177843714048000,3201186852864000

%N Integers of the form x!*y!/(x! + y!) where x, y are positive integers.

%C The sequence contains A001710 when x=y.

%e 630 is in the sequence because with x=6 and y=7, 6!7!/(6!+7!) = 720*5040/(720+5040)=630.

%o (PARI) lista(nn) = select(x->(denominator(x)==1), setbinop((x,y)->x!*y!/(x! + y!), [1..nn])) \\ _Michel Marcus_, Jun 27 2024

%Y Cf. A001710.

%K nonn

%O 1,2

%A _Michel Lagneau_, Jun 27 2024