A145123 Numbers n such that there exists x in N : (x+1)^3-x^3=19*n^2.

1, 301, 90901, 27451801, 8290353001, 2503659154501, 756096774306301, 228338722181348401, 68957538001992910801, 20824948137879677713501, 6289065380101660676566501, 1899276919842563644645369801

Offset: 1

Author

Richard Choulet, Oct 02 2008

Keywords

• easy
• nonn

Examples

			a(1)=1 because 3^3-2^3=19*1.
		

Links

• Vincenzo Librandi, Table of n, a(n) for n = 1..100
• Index entries for linear recurrences with constant coefficients, signature (302,-1).

Crossrefs

Cf. A145124.

Programs

Mathematica

CoefficientList[Series[(1 - x)/(1 - 302 x + x^2), {x, 0, 20}], x] (* Vincenzo Librandi, Oct 18 2014 *)

PARI

Vec(-x*(-1+x)/(1-302*x+x^2) + O(x^30)) \\ Colin Barker, Oct 18 2014

Formula

a(n+2) = 302*a(n+1)-a(n).

G.f.: -x*(-1+x) / ( 1-302*x+x^2 ). - R. J. Mathar, Nov 27 2011

Extensions

Editing and more terms from Colin Barker, Oct 18 2014