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

Author

Parthasarathy Nambi, Oct 13 2004

Keywords

• sign
• easy

Examples

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

Links

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

Crossrefs

See A091515.

Programs

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 *)

PARI

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

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

Extensions

More terms from Stefan Steinerberger, Feb 15 2006