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 A181193 #7 Feb 27 2018 05:29:38 %S A181193 1,42,3532,352184,36372976,3777546912,392658046912,40820345224064, %T A181193 4243729567634176,441184342397471232,45866192670977108992, %U A181193 4768319236090599225344,495721734753595527294976 %N A181193 Number of n X 6 matrices containing a permutation of 1..n*6 in increasing order rowwise, columnwise, diagonally and (downwards) antidiagonally. %C A181193 Column 6 of A181196. %H A181193 R. H. Hardin, <a href="/A181193/b181193.txt">Table of n, a(n) for n=1..100</a> %F A181193 Empirical: a(n) = 120*a(n-1) - 1672*a(n-2) + 544*a(n-3) - 6672*a(n-4) + 256*a(n-5). %F A181193 Empirical g.f.: x*(1 - 78*x + 164*x^2 - 1976*x^3 + 224*x^4) / ((1 - 16*x)*(1 - 104*x + 4*x^2)*(1 + 4*x^2)). - _Colin Barker_, Feb 27 2018 %e A181193 Some solutions for 4 X 6: %e A181193 ..1..2..3..4..5..6....1..2..3..4..5..6....1..2..3..4..5..6....1..2..3..4..5..6 %e A181193 ..7..8..9.10.11.12....7..8..9.10.11.12....7..8..9.10.11.12....7..8..9.10.11.12 %e A181193 .13.14.15.16.17.18...13.14.15.17.19.20...13.14.15.17.19.21...13.14.15.17.19.22 %e A181193 .19.20.21.22.23.24...16.18.21.22.23.24...16.18.20.22.23.24...16.18.20.21.23.24 %Y A181193 Cf. A181196. %K A181193 nonn %O A181193 1,2 %A A181193 _R. H. Hardin_, Oct 10 2010