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%I #12 Aug 16 2015 12:04:01
%S 4,39204,376437604,3614553835204,34706945549192004,
%T 333256087548787788004,3199924917936514791223204,
%U 30725678728770327476537417604,295027963953727766493197492611204,2832858479158015285097354847515364004,27201106821847298813777034752645032556004
%N Positive squares (A000290) that are octagonal numbers (A000567) divided by 2.
%C Intersection of A000290 and A033579 (even octagonal numbers divided by 2). - _Michel Marcus_, Jun 20 2015
%H Colin Barker, <a href="/A259160/b259160.txt">Table of n, a(n) for n = 1..251</a>
%H <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (9603,-9603,1).
%F G.f.: -4*x*(x^2+198*x+1) / ((x-1)*(x^2-9602*x+1)).
%e 4 is in the sequence because 4 is the 2nd square, and 2*4 is the 2nd octagonal number.
%t LinearRecurrence[{9603, -9603, 1}, {4, 39204, 376437604}, 20] (* _Vincenzo Librandi_, Jun 20 2015 *)
%o (PARI) Vec(-4*x*(x^2+198*x+1)/((x-1)*(x^2-9602*x+1)) + O(x^20))
%Y Cf. A000290, A000567, A033579, A259156-A259159, A259161-A259167.
%K nonn,easy
%O 1,1
%A _Colin Barker_, Jun 19 2015