This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A024169 #21 May 19 2018 18:55:36
%S A024169 0,0,1,3,5,8,11,15,19,24,29,34,41,47,54,62,70,79,88,98,108,119,130,
%T A024169 141,154,166,179,193,207,222,237,253,269,286,303,320,339,357,376,396,
%U A024169 416,437,458,480,502
%N A024169 Integer part of ((2nd elementary symmetric function of 1,2,...,n)/(1+2+...+n)).
%H A024169 Ivan Neretin, <a href="/A024169/b024169.txt">Table of n, a(n) for n = 1..10000</a>
%F A024169 From _R. J. Mathar_, Sep 15 2009: (Start)
%F A024169 a(n) = floor( A000914(n-1)/A000217(n)).
%F A024169 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)
%F A024169 a(n) = floor((1/12)*(n - 1)*(3*n + 2)). - _Ivan Neretin_, May 19 2018
%p A024169 seq(floor((1/12)*(n-1)*(3*n+2)),n=1..50); # _Muniru A Asiru_, May 19 2018
%t A024169 Table[Floor[1/12 (n - 1) (3 n + 2)], {n, 45}] (* _Ivan Neretin_, May 19 2018 *)
%o A024169 (GAP) List([1..50],n->Int((1/12)*(n-1)*(3*n+2))); # _Muniru A Asiru_, May 19 2018
%K A024169 nonn
%O A024169 1,4
%A A024169 _Clark Kimberling_