A376057 a(n) is the denominator of the sum S(n) defined in A376056.

1, 2, 14, 994, 6917246, 430634636937890, 2039908095836912108987531110990, 54095925512992695768212345567905438957243461489279855615252290

Offset

0,2

Links

Alois P. Heinz, Table of n, a(n) for n = 0..11

Formula

a(n+1) = (2*n+1)*a(n)^2 + a(n), with a(0) = 1.

Example

The first few values of S(n) are 0/1, 1/2, 13/14, 993/994, 6917245/6917246, 430634636937889/430634636937890, ...

Maple

a:= proc(n) a(n):= `if`(n=0, 1, ((2*n-1)*a(n-1)+1)*a(n-1)) end:
seq(a(n), n=0..7);  # Alois P. Heinz, Oct 18 2024

Mathematica

RecurrenceTable[{a[n+1] == (2*n+1)*a[n]^2 + a[n], a[0] == 1}, a, {n, 0, 7}] (* Amiram Eldar, Sep 15 2024 *)

Crossrefs

Cf. A374663, A375516, A375531, A375532, A375781, A375522, A376048-A376056.

Sequence in context: A225163 A319540 A190634 * A130421 A347908 A227403

Adjacent sequences: A376054 A376055 A376056 * A376058 A376059 A376060

Keyword

nonn,base,frac

Author

N. J. A. Sloane, Sep 14 2024.

Extensions

a(0)=1 prepended by Alois P. Heinz, Oct 18 2024

Status

approved