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 A112503 #5 Jul 08 2025 17:24:39 %S A112503 1,20,225,1882,13070,79872,444902,2311828,11388999,53820068,246112783, %T A112503 1096379070,4782801180,20515294320,86808499020,363304109640, %U A112503 1507010836605,6206407299540,25412183425165,103563957886370 %N A112503 Fourth column of triangle A112500. %C A112503 For a combinatorial formula see A112500, case k=4. %H A112503 <a href="/index/Rec#order_10">Index entries for linear recurrences with constant coefficients</a>, signature (20,-175,882,-2835,6072,-8777,8458,-5204,1848,-288). %F A112503 G.f.: 1/product((1-j*x)^(5-j), j=1..4) = 1/(((1-x)^4)*((1-2*x)^3)*((1-3*x)^2)*(1-4*x)). %F A112503 a(n) = 7813/324 + (2251/432)*(n+1) + (31/36)*binomial(n+2, 2) +(1/12)*binomial(n+3, 3) +(-1344 -256*(n+1) - 64*binomial(n+2, 2))*2^n + (6561/4 - (6561/16)*(n+1))*3^n + (32768/81)*4^n, n>=0 (from partial fractions for g.f.). %K A112503 nonn,easy %O A112503 0,2 %A A112503 _Wolfdieter Lang_, Oct 14 2005