A376767 a(1) = 1; thereafter, a(n) = c*a(n-1)^2 + a(n-1), where c=4 if n is even, c=2 if n is odd.

1, 5, 55, 12155, 295500205, 349281484915668305, 243995111409788451714836854478814355, 238134457567500314773144369878965950377595240310563734057802960695078455

Offset

1,2

Comments

Used to construct A376768.

Links

Paolo Xausa, Table of n, a(n) for n = 1..11

Example

a(3) = 2*a(2)^2 + a(2) = 55.

Mathematica

Module[{n = 1}, NestList[If[OddQ[++n], 2, 4]*#^2 + # &, 1, 8]] (* Paolo Xausa, Dec 16 2024 *)

Crossrefs

Cf. A376768.

Sequence in context: A068666 A082780 A063855 * A081785 A144996 A129440

Adjacent sequences: A376764 A376765 A376766 * A376768 A376769 A376770

Keyword

nonn

Author

N. J. A. Sloane, Nov 03 2024

Status

approved