A259165 Positive heptagonal numbers (A000566) that are pentagonal numbers (A000326) divided by 2.

540, 125482435, 29152330292086, 6772727677992549813, 1573453639577432827392256, 365547896447135621647431177175, 84924818396817988252797073116286650, 19729903659220000770419185998874515952681, 4583690677832384200588508141377728222042497188

Offset: 1

Author

Colin Barker, Jun 19 2015

Keywords

• nonn
• easy

Comments

Intersection of A000566 and A193866 (even pentagonal numbers divided by 2). - Michel Marcus, Jun 20 2015

Examples

			540 is in the sequence because 540 is the 15th heptagonal number, and 2*540 is the 27th pentagonal number.
		

Links

• Colin Barker, Table of n, a(n) for n = 1..186
• Index entries for linear recurrences with constant coefficients, signature (232323,-232323,1).

Crossrefs

Cf. A000326, A000566, A193866, A259156-A259164, A259166, A259167.

Programs

Mathematica

LinearRecurrence[{232323, -232323, 1}, {540, 125482435, 29152330292086}, 20] (* Vincenzo Librandi, Jun 20 2015 *)

PARI

Vec(-x*(x^2+28015*x+540)/((x-1)*(x^2-232322*x+1)) + O(x^20))

Formula

G.f.: -x*(x^2+28015*x+540) / ((x-1)*(x^2-232322*x+1)).