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 A024391 #11 Aug 19 2019 11:38:47
%S A024391 10,66,231,595,1275,2415,4186,6786,10440,15400,21945,30381,41041,
%T A024391 54285,70500,90100,113526,141246,173755,211575,255255,305371,362526,
%U A024391 427350,500500,582660,674541,776881,890445,1016025,1154440,1306536,1473186,1655290
%N A024391 2nd elementary symmetric function of the first n+1 positive integers congruent to 2 mod 3.
%H A024391 <a href="/index/Rec#order_05">Index entries for linear recurrences with constant coefficients</a>, signature (5,-10,10,-5,1).
%F A024391 a(n) = n*(n+1)*(3*n+2)*(3*n+5)/8.
%F A024391 O.g.f.: -x*(10+16*x+x^2)/(-1+x)^5 . - _R. J. Mathar_, Feb 14 2008
%t A024391 LinearRecurrence[{5,-10,10,-5,1},{10,66,231,595,1275},50] (* _Harvey P. Dale_, Aug 19 2019 *)
%K A024391 nonn,easy
%O A024391 1,1
%A A024391 _Clark Kimberling_