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

1,1

Comments

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

Links

Colin Barker, Table of n, a(n) for n = 1..251

Index entries for linear recurrences with constant coefficients, signature (9603,-9603,1).

Formula

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

Example

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

Mathematica

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

Prog

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

Crossrefs

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

Sequence in context: A295817 A118859 A323725 * A076913 A101450 A101439

Adjacent sequences: A259159 A259160 A259161 * A259163 A259164 A259165

Keyword

nonn,easy

Author

Colin Barker, Jun 19 2015

Status

approved