A259162 Positive hexagonal numbers (A000384) that are pentagonal numbers (A000326) divided by 2.

6, 58311, 559902916, 5376187741821, 51622154137063026, 495675918647891434531, 4759480119234899417304336, 45700527609217585557064800441, 438816461344227137284036796530846, 4213515616126741362983735763224383551, 40458176507232509223142693514443734326556

Offset: 1

Author

Colin Barker, Jun 19 2015

Keywords

• nonn
• easy

Comments

Intersection of A000384 and A193866 (even pentagonal numbers divided by 2). - Michel Marcus, Jun 20 2015

Examples

			6 is in the sequence because 6 is the 2nd hexagonal number, and 2*6 is the 3rd pentagonal number.
		

Links

• Colin Barker, Table of n, a(n) for n = 1..251
• Index entries for linear recurrences with constant coefficients, signature (9603,-9603,1).

Crossrefs

Cf. A000326, A000384, A193866, A259156-A259161, A259163-A259167.

Programs

Mathematica

LinearRecurrence[{9603, -9603, 1}, {6, 58311, 559902916}, 20] (* Vincenzo Librandi, Jun 20 2015 *)

PARI

Vec(-x*(x^2+693*x+6)/((x-1)*(x^2-9602*x+1)) + O(x^20))

Formula

G.f.: -x*(x^2+693*x+6) / ((x-1)*(x^2-9602*x+1)).