A024201 [ (2nd elementary symmetric function of S(n))/(first elementary symmetric function of S(n)) ], where S(n) = {first n+1 odd positive integers}.

0, 2, 5, 9, 14, 19, 26, 34, 43, 53, 64, 75, 88, 102, 117, 133, 150, 167, 186, 206, 227, 249, 272, 295, 320, 346, 373, 401, 430, 459, 490, 522, 555, 589, 624, 659, 696, 734, 773, 813, 854, 895, 938, 982, 1027, 1073, 1120, 1167, 1216, 1266, 1317, 1369, 1422, 1475

Offset

1,2

Links

Table of n, a(n) for n=1..54.

Index entries for linear recurrences with constant coefficients, signature (2,-1,0,0,0,1,-2,1).

Formula

G.f.: x^2*(x^6-2*x^5-x^3-x^2-x-2) / ((x-1)^3*(x+1)*(x^2-x+1)*(x^2+x+1)). - Colin Barker, Aug 15 2014

a(n) = floor( A024196(n)/(1+n)^2). - R. J. Mathar, Sep 23 2016

a(n) = (n^2 + n - 2)/2 - floor(n/6), n>=1. - Muslim Alaa, Apr 01 2026

Mathematica

LinearRecurrence[{2, -1, 0, 0, 0, 1, -2, 1}, {0, 2, 5, 9, 14, 19, 26, 34}, 55] (* Hugo Pfoertner, Mar 30 2026 *)

Crossrefs

Sequence in context: A112265 A025281 A160663 * A110443 A130029 A266450

Adjacent sequences: A024198 A024199 A024200 * A024202 A024203 A024204

Keyword

nonn,easy

Author

Clark Kimberling

Status

approved