A323717 a(n) = Product_{k=0..n} (n! + k!).

2, 4, 36, 4704, 23400000, 7778123781120, 245221791787632844800, 980866487456532919096049664000, 647456833933936977045736601678008811520000, 89423837415458106416291101560480526982914768896000000000

Offset

0,1

Links

G. C. Greubel, Table of n, a(n) for n = 0..29

Formula

a(n) ~ 2^((n+3)/2) * Pi^((n+1)/2) * n^((n+1)*(2*n+1)/2) / exp(n^2 + n - 1/12).

a(n) ~ 2 * (n!)^(n+1). - Vaclav Kotesovec, Mar 28 2019

Mathematica

Table[Product[n!+k!, {k, 0, n}], {n, 0, 10}]

Prog

(Magma) F:= Factorial; [(&*[F(n) + F(j): j in [0..n]]): n in [0..20]]; // G. C. Greubel, Aug 30 2023
(SageMath) f=factorial; [product(f(n) + f(k) for k in range(n+1)) for n in range(21)] # G. C. Greubel, Aug 30 2023

Crossrefs

Cf. A036740, A203308, A203483, A323702.

Sequence in context: A081976 A326932 A063184 * A212775 A115250 A018304

Adjacent sequences: A323714 A323715 A323716 * A323718 A323719 A323720

Keyword

nonn

Author

Vaclav Kotesovec, Jan 25 2019

Status

approved