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 A084899 #5 Jun 13 2015 00:51:05 %S A084899 0,1,9,42,152,480,1392,3808,9984,25344,62720,152064,362496,851968, %T A084899 1978368,4546560,10354688,23396352,52494336,117047296,259522560, %U A084899 572522496,1257242624,2749366272,5989466112,13002342400,28135391232 %N A084899 Binomial transform of heptagonal numbers A000566. %C A084899 Binomial transform is A084900. 2nd binomial transform of (0,1,5,0,0,0,....). %H A084899 <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (6,-12,8). %F A084899 G.f.: x(1 + 3x)/(1 - 2x)^3; a(n)=2^(n - 2)*n(5n - 1)/2. %K A084899 easy,nonn %O A084899 0,3 %A A084899 _Paul Barry_, Jun 10 2003