A063402 a(0)=0; a(1)=1; a(2)=2; a(n)= a(n-1) + a(n-2)*a(n-3).

0, 1, 2, 2, 4, 8, 16, 48, 176, 944, 9392, 175536, 9041584, 1657675696, 1588781164720, 14989602831307184, 2633698912621747952304, 23815201278713350097371300784, 39478100701260806183512640492975852720

Offset

0,3

Links

Harry J. Smith, Table of n, a(n) for n = 0..29

Mathematica

nxt[{a_, b_, c_}]:={b, c, c+a*b}; NestList[nxt, {0, 1, 2}, 20][[All, 1]] (* Harvey P. Dale, Oct 16 2020 *)

Prog

(PARI) { for (n = 0, 29, if (n>2, a=a1 + a2*a3; a3=a2; a2=a1; a1=a, if (n==0, a=a3=0; a2=1; a1=2, if (n==1, a=1, a=2))); write("b063402.txt", n, " ", a) ) } \\ Harry J. Smith, Aug 20 2009

Crossrefs

Cf. A006888.

Sequence in context: A123593 A122748 A108774 * A175195 A369289 A139800

Adjacent sequences: A063399 A063400 A063401 * A063403 A063404 A063405

Keyword

nonn,easy

Author

Olivier Gérard, Jul 16 2001

Status

approved