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A259160 Positive squares (A000290) that are octagonal numbers (A000567) divided by 2. 3
4, 39204, 376437604, 3614553835204, 34706945549192004, 333256087548787788004, 3199924917936514791223204, 30725678728770327476537417604, 295027963953727766493197492611204, 2832858479158015285097354847515364004, 27201106821847298813777034752645032556004 (list; graph; refs; listen; history; text; internal format)
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

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Last modified August 13 07:13 EDT 2022. Contains 356078 sequences. (Running on oeis4.)