A109172 Recursive form of A109845 without a(2)=3.

2, 7, 41, 1723, 2967005, 8803121637031, 77494950556354550188857929

Offset

1,1

Links

Table of n, a(n) for n=1..7.

Formula

a(1)=2, a(n)=a(n-1)^2+(-1)^n*a(n-1)+(-1)^n

Maple

a := proc(n) option remember; if n=1 then 2 else a(n-1)^2+(-1)^n*a(n-1)+(-1)^n fi end:

Mathematica

nxt[{n_, a_}]:={n+1, a^2+(-1)^(n+1) a+(-1)^(n+1)}; Transpose[NestList[nxt, {1, 2}, 10]][[2]] (* Harvey P. Dale, Dec 15 2012 *)

Crossrefs

Cf. A109845.

Sequence in context: A159315 A191601 A265772 * A131682 A366453 A345368

Adjacent sequences: A109169 A109170 A109171 * A109173 A109174 A109175

Keyword

nonn

Author

Walter Kehowski, Aug 18 2005

Status

approved