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 A112502 #5 Jul 08 2025 12:07:11 %S A112502 1,10,60,282,1149,4272,14932,49996,162369,515886,1613316,4987542, %T A112502 15290461,46592452,141350412,427459320,1289718225,3884883570, %U A112502 11688205420,35135919730,105558754461,316995030840,951656181540 %N A112502 Third column of triangle A112500. %C A112502 For a combinatorial formula see A112500, case k=3. %H A112502 <a href="/index/Rec#order_06">Index entries for linear recurrences with constant coefficients</a>, signature (10,-40,82,-91,52,-12). %F A112502 G.f.: 1/product((1-j*x)^(4-j), j=1..3) = 1/(((1-x)^3)*((1-2*x)^2)*(1-3*x)). %F A112502 a(n) = - 81/8 - (11/4)*(n+1) - (1/2)*binomial(n+2, 2) - 16*(n+1)*2^n + (243/8)*3^n, n>=0 (from partial fractions for g.f.). %Y A112502 Cf. A000295 (second column). %K A112502 nonn,easy %O A112502 0,2 %A A112502 _Wolfdieter Lang_, Oct 14 2005