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

Author

Colin Barker, Jun 19 2015

Keywords

• nonn
• easy

Comments

Intersection of A000290 and A033579 (even octagonal numbers divided by 2). - Michel Marcus, Jun 20 2015

Examples

			4 is in the sequence because 4 is the 2nd square, and 2*4 is the 2nd octagonal 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. A000290, A000567, A033579, A259156-A259159, A259161-A259167.

Programs

Mathematica

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

PARI

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

Formula

G.f.: -4*x*(x^2+198*x+1) / ((x-1)*(x^2-9602*x+1)).