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 A024401 #11 Jul 07 2019 02:49:50
%S A024401 1,3,6,11,16,22,30,38,47,58,69,81,95,109,124,141,158,176,196,216,237,
%T A024401 260,283,307,333,359,386,415,444,474,506,538,571,606,641,677,715,753,
%U A024401 792,833,874,916,960
%N A024401 a(n) = [ (3rd elementary symmetric function of S(n))/(2nd elementary symmetric function of S(n)) ], where S(n) = {first n+2 positive integers congruent to 2 mod 3}.
%F A024401 Conjecture: a(n) = 2*a(n-1) - a(n-2) + a(n-3) - 2*a(n-4) + a(n-5). G.f. x*(-1-x-x^3-x^2+x^4) / ( (1+x+x^2)*(x-1)^3 ). - _R. J. Mathar_, Oct 08 2011
%F A024401 a(n) = floor(A024392(n) / A024391(n+1)). - _Sean A. Irvine_, Jul 07 2019
%Y A024401 Cf. A024391, A024392.
%K A024401 nonn
%O A024401 1,2
%A A024401 _Clark Kimberling_