A259160 Positive squares (A000290) that are octagonal numbers (A000567) divided by 2.

4, 39204, 376437604, 3614553835204, 34706945549192004, 333256087548787788004, 3199924917936514791223204, 30725678728770327476537417604, 295027963953727766493197492611204, 2832858479158015285097354847515364004, 27201106821847298813777034752645032556004

Offset

1,1

Comments

Intersection of A000290 and A033579 (even octagonal 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.: -4*x*(x^2+198*x+1) / ((x-1)*(x^2-9602*x+1)).

Example

4 is in the sequence because 4 is the 2nd square, and 2*4 is the 2nd octagonal number.

Mathematica

LinearRecurrence[{9603, -9603, 1}, {4, 39204, 376437604}, 20] (* Vincenzo Librandi, Jun 20 2015 *)

Prog

(PARI) Vec(-4*x*(x^2+198*x+1)/((x-1)*(x^2-9602*x+1)) + O(x^20))

Crossrefs

Cf. A000290, A000567, A033579, A259156-A259159, A259161-A259167.

Sequence in context: A275684 A001376 A053937 * A173138 A275587 A132638

Adjacent sequences: A259157 A259158 A259159 * A259161 A259162 A259163

Keyword

nonn,easy

Author

Colin Barker, Jun 19 2015

Status

approved