A118558 a(n) = (2^n-1)^4 - 2.

-2, -1, 79, 2399, 50623, 923519, 15752959, 260144639, 4228250623, 68184176639, 1095222947839, 17557851463679, 281200199450623, 4501401006735359, 72040003462430719, 1152780773560811519, 18445618199572250623, 295138898083176775679, 4722294425687923097599

Offset

0,1

Links

Table of n, a(n) for n=0..18.

Index entries for linear recurrences with constant coefficients, signature (31,-310,1240,-1984,1024).

Formula

a(n) = (2^n - 1)^4 - 2.

G.f.: (1984*x^4-2120*x^3+510*x^2-61*x+2) / ((x-1)*(2*x-1)*(4*x-1)*(8*x-1)*(16*x-1)). - Colin Barker, Apr 30 2013

Example

a(0) = (2^0 - 1)^4 - 2 = 0^4 - 2 = -2.
a(1) = (2^1 - 1)^4 - 2 = 1^4 - 2 = -1.
a(2) = (2^2 - 1)^4 - 2 = 3^4 - 2 = 79.

Mathematica

(2^Range[0, 20] - 1)^4 - 2 (* Paolo Xausa, Apr 19 2024 *)

Prog

(PARI) a(n)=(2^n-1)^4-2 \\ Charles R Greathouse IV, Feb 19 2016

Crossrefs

Cf. A091516, A091515, A098878, A091514.

Cf. A093112, A098878.

Sequence in context: A247793 A067276 A118580 * A095837 A095835 A147805

Adjacent sequences: A118555 A118556 A118557 * A118559 A118560 A118561

Keyword

easy,sign,changed

Author

Jonathan Vos Post, May 03 2006

Extensions

Offset changed to 0 by Paolo Xausa, Apr 19 2024

Status

approved