A210981 A062725 and positive terms of A051682 interleaved.

0, 1, 7, 11, 23, 30, 48, 58, 82, 95, 125, 141, 177, 196, 238, 260, 308, 333, 387, 415, 475, 506, 572, 606, 678, 715, 793, 833, 917, 960, 1050, 1096, 1192, 1241, 1343, 1395, 1503, 1558, 1672, 1730, 1850, 1911, 2037, 2101, 2233, 2300, 2438, 2508, 2652, 2725, 2875, 2951, 3107, 3186, 3348

Offset

0,3

Comments

Vertex number of a square spiral similar to A195160.

Links

Table of n, a(n) for n=0..54.

Index entries for linear recurrences with constant coefficients, signature (1,2,-2,-1,1).

Formula

G.f.: -x*(1+6*x+2*x^2) / ( (1+x)^2*(x-1)^3 ). - R. J. Mathar, Aug 07 2012

a(n) = ( 18*n^2+14*n-5+(6*n+5)*(-1)^n )/16. - Luce ETIENNE, Oct 14 2014

Mathematica

LinearRecurrence[{1, 2, -2, -1, 1}, {0, 1, 7, 11, 23}, 70] (* Harvey P. Dale, Jun 29 2023 *)

Crossrefs

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

Cf. A051682, A062725, A195160.

Sequence in context: A067790 A271043 A089056 * A372303 A255769 A175625

Adjacent sequences: A210978 A210979 A210980 * A210982 A210983 A210984

Keyword

nonn,easy

Author

Omar E. Pol, Aug 03 2012

Status

approved