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 A123293 #2 Oct 09 2013 02:24:29 %S A123293 0,0,128,512,1280,2560,4480,7168,10752,15360,21120,28160 %N A123293 Number of permutations of n distinct letters (ABCD...) each of which appears 4 times and having n-3 fixed points. %e A123293 1 %e A123293 0, "0", 0, 0, 1 %e A123293 1, 0, 16, 0, 36, "0", 16, 0, 1 %e A123293 346, 1824, 4536, 7136, 7947, 6336, 3936, 1728, 684, "128", 48, 0, 1 %e A123293 748521, 3662976, 8607744, 12880512, 13731616, 11042688, 6928704, 3458432, 1395126, 453888, 122016, 25344, 4824, "512", 96, 0, 1 %e A123293 3993445276, 18743463360, 42506546320, 61907282240, 64917874125, 52087325696, 33176621920, 17181584640, 7352761180, 2628808000, 790912656, 201062080, 43284010, 7873920, 1216000, 154496, 17640, "1280", 160, 0, 1 %e A123293 etc.. %p A123293 p := (x, k)->k!^2*sum(x^j/((k-j)!^2*j!), j=0..k); R := (x, n, k)->p(x, k)^n; f := (t, n, k)->sum(coeff(R(x, n, k), x, j)*(t-1)^j*(n*k-j)!, j=0..n*k); for n from 0 to 5 do seq(coeff(f(t, n, 4), t, m)/4!^n, m=0..4*n); od; %Y A123293 Cf. A059060. %K A123293 nonn %O A123293 0,3 %A A123293 _Zerinvary Lajos_, Nov 07 2006