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 A211709 #11 Jan 16 2024 18:29:18 %S A211709 1,1,1,1,4,1,1,18,18,1,1,108,588,108,1,1,780,30240,30240,780,1,1,6600, %T A211709 2277600,17427192,2277600,6600,1,1,63840,234440280,17741309400, %U A211709 17741309400,234440280,63840,1,1,693840,31448589480 %N A211709 T(n,k) = number of n X k nonnegative integer arrays with new values 0 upwards introduced in row major order and every value unique in its row and column. %e A211709 Table starts: %e A211709 1 1 1 1 1 1 1 1 1 %e A211709 1 4 18 108 780 6600 63840 693840 %e A211709 1 18 588 30240 2277600 234440280 31448589480 %e A211709 1 108 30240 17427192 17741309400 %e A211709 1 780 2277600 17741309400 %e A211709 1 6600 234440280 %e A211709 1 63840 %e A211709 1 %e A211709 Some solutions for n=4, k=4: %e A211709 0 1 2 3 0 1 2 3 0 1 2 3 0 1 2 3 0 1 2 3 %e A211709 1 4 0 2 1 2 0 4 4 2 0 1 1 0 3 2 1 0 3 2 %e A211709 2 0 5 1 2 0 1 5 1 0 3 2 2 3 0 4 4 2 0 1 %e A211709 3 2 1 4 3 4 5 0 2 3 1 0 3 2 1 0 5 3 1 0 %Y A211709 Column 2 is A144085. %K A211709 nonn,tabl %O A211709 1,5 %A A211709 _R. H. Hardin_, Apr 19 2012