A376049 a(n) is the denominator of the sum S(n) defined in A376048.

1, 4, 20, 1620, 2626020, 34479907828020, 10699776394458828344981911620, 228970429782836729250563232145698649718622958323963960420, 314564746289621790478499809054644383073494124885364231904506529162346525698245870188461228508418377184391923418820

Offset

0,2

Links

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

Formula

a(n+1) = b(n+1)*a(n)^2 + a(n), with a(1) = 4, where b(n) is defined in A376048.

Example

The first few values of S(n) are 0/1, 3/4, 19/20, 1619/1620, 2626019/2626020, 34479907828019/34479907828020, ...

Crossrefs

Cf. A000796, A375531, A375532, A376048.

Sequence in context: A144989 A012841 A074195 * A332867 A217369 A146342

Adjacent sequences: A376046 A376047 A376048 * A376050 A376051 A376052

Keyword

nonn,base,frac

Author

N. J. A. Sloane, Sep 13 2024.

Extensions

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

Status

approved