A098878 a(n) = (2^n - 1)^3 - 2.

-2, -1, 25, 341, 3373, 29789, 250045, 2048381, 16581373, 133432829, 1070599165, 8577357821, 68669157373, 549554511869, 4397241253885, 35181150961661, 281462092005373, 2251748274470909, 18014192351838205

Offset

0,1

Links

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

Index entries for linear recurrences with constant coefficients, signature (15,-70,120,-64).

Formula

G.f.: (136*x^3-100*x^2+29*x-2) / ((x-1)*(2*x-1)*(4*x-1)*(8*x-1)). - Colin Barker, Apr 30 2013

Example

a(2) = (2^2 - 1)^3 - 2 = 25.

Mathematica

Table[(2^n - 1)^3 - 2, {n, 0, 20}] (* Stefan Steinerberger, Feb 15 2006 *)
(2^Range[0, 20]-1)^3-2 (* or *) LinearRecurrence[{15, -70, 120, -64}, {-2, -1, 25, 341}, 30] (* Harvey P. Dale, Jan 29 2016 *)

Prog

(PARI) a(n) = (2^n - 1)^3 - 2; \\ Joerg Arndt, Apr 30 2013

Crossrefs

See A091515.

Sequence in context: A087452 A317385 A366048 * A235031 A138955 A089963

Adjacent sequences: A098875 A098876 A098877 * A098879 A098880 A098881

Keyword

sign,easy

Author

Parthasarathy Nambi, Oct 13 2004

Extensions

More terms from Stefan Steinerberger, Feb 15 2006

Status

approved