A210977 A005475 and positive terms of A000566 interleaved.

0, 1, 3, 7, 11, 18, 24, 34, 42, 55, 65, 81, 93, 112, 126, 148, 164, 189, 207, 235, 255, 286, 308, 342, 366, 403, 429, 469, 497, 540, 570, 616, 648, 697, 731, 783, 819, 874, 912, 970, 1010, 1071, 1113, 1177, 1221, 1288, 1334, 1404, 1452, 1525, 1575, 1651, 1703, 1782, 1836, 1918, 1974, 2059

Offset

0,3

Comments

Vertex number of a square spiral similar to A085787.

Partial sums of the sequence formed by A005843 and A016777 interleaved.

Links

Paolo Xausa, Table of n, a(n) for n = 0..10000

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

Formula

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

a(n) = (10*n^2+6*n-1-(2*n-1)*(-1)^n)/16. - Luce ETIENNE, Oct 04 2014

Mathematica

A210977[n_] := (10*n^2 + 6*n - 1 - (2*n - 1)*(-1)^n)/16;
Array[A210977, 60, 0] (* Paolo Xausa, May 18 2026 *)
(* Alternative: *)
LinearRecurrence[{1, 2, -2, -1, 1}, {0, 1, 3, 7, 11}, 60] (* Paolo Xausa, May 18 2026 *)

Crossrefs

Members of this family are A093005, this sequence, A006578, A210978, A181995, A210981, A210982.

Cf. A000566, A005843, A016777, A085787,

Sequence in context: A373631 A363359 A190711 * A049792 A062851 A063437

Adjacent sequences: A210974 A210975 A210976 * A210978 A210979 A210980

Keyword

nonn,easy

Author

Omar E. Pol, Aug 03 2012

Status

approved