A024169 Integer part of ((2nd elementary symmetric function of 1,2,...,n)/(1+2+...+n)).

0, 0, 1, 3, 5, 8, 11, 15, 19, 24, 29, 34, 41, 47, 54, 62, 70, 79, 88, 98, 108, 119, 130, 141, 154, 166, 179, 193, 207, 222, 237, 253, 269, 286, 303, 320, 339, 357, 376, 396, 416, 437, 458, 480, 502

Offset: 1

Author

Clark Kimberling

Keywords

• nonn

Links

• Ivan Neretin, Table of n, a(n) for n = 1..10000

Programs

GAP

List([1..50],n->Int((1/12)*(n-1)*(3*n+2))); # Muniru A Asiru, May 19 2018

Maple

seq(floor((1/12)*(n-1)*(3*n+2)),n=1..50); # Muniru A Asiru, May 19 2018

Mathematica

Table[Floor[1/12 (n - 1) (3 n + 2)], {n, 45}] (* Ivan Neretin, May 19 2018 *)

Formula

From R. J. Mathar, Sep 15 2009: (Start)

a(n) = floor( A000914(n-1)/A000217(n)).

G.f.: x^3*(-1-x-x^5-2*x^7+x^4+x^8)/((x^2+1) * (1+x+x^2) * (x^4-x^2+1) * (x-1)^3). (End)

a(n) = floor((1/12)*(n - 1)*(3*n + 2)). - Ivan Neretin, May 19 2018