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A186029 and positive terms of A001106 interleaved.
6

%I #17 Jun 18 2017 02:18:53

%S 0,1,5,9,17,24,36,46,62,75,95,111,135,154,182,204,236,261,297,325,365,

%T 396,440,474,522,559,611,651,707,750,810,856,920,969,1037,1089,1161,

%U 1216,1292,1350,1430,1491,1575,1639,1727,1794,1886,1956,2052,2125,2225,2301

%N A186029 and positive terms of A001106 interleaved.

%C Vertex number of a square spiral similar to A118277.

%H <a href="/index/Rec#order_05">Index entries for linear recurrences with constant coefficients</a>, signature (1,2,-2,-1,1).

%F a(n) = (3*(-1+(-1)^n)+2*(5+(-1)^n)*n+14*n^2)/16. a(n) = a(n-1)+2*a(n-2)-2*a(n-3)-a(n-4)+a(n-5). G.f.: -x*(2*x^2+4*x+1) / ((x-1)^3*(x+1)^2). - _Colin Barker_, Sep 15 2013

%o (PARI) Vec(-x*(2*x^2+4*x+1)/((x-1)^3*(x+1)^2) + O(x^100)) \\ _Colin Barker_, Sep 15 2013

%Y Members of this family are A093005, A210977, A006578, this sequence, A181995, A210981, A210982.

%Y Cf. A001106, A118277, A186029, A195020, A195024.

%K nonn,easy

%O 0,3

%A _Omar E. Pol_, Aug 03 2012

%E More terms from _Colin Barker_, Sep 15 2013