A210981 - OEIS

%I #19 Jun 29 2023 20:55:38

%S 0,1,7,11,23,30,48,58,82,95,125,141,177,196,238,260,308,333,387,415,

%T 475,506,572,606,678,715,793,833,917,960,1050,1096,1192,1241,1343,

%U 1395,1503,1558,1672,1730,1850,1911,2037,2101,2233,2300,2438,2508,2652,2725,2875,2951,3107,3186,3348

%N A062725 and positive terms of A051682 interleaved.

%C Vertex number of a square spiral similar to A195160.

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

%F G.f.: -x*(1+6*x+2*x^2) / ( (1+x)^2*(x-1)^3 ). - _R. J. Mathar_, Aug 07 2012

%F a(n) = ( 18*n^2+14*n-5+(6*n+5)*(-1)^n )/16. - _Luce ETIENNE_, Oct 14 2014

%t LinearRecurrence[{1,2,-2,-1,1},{0,1,7,11,23},70] (* _Harvey P. Dale_, Jun 29 2023 *)

%Y Members of this family are A093005, A210977, A006578, A210978, A181995, this sequence, A210982.

%Y Cf. A051682, A062725, A195160.

%K nonn,easy

%O 0,3

%A _Omar E. Pol_, Aug 03 2012