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 A278431 #4 Nov 22 2016 06:52:42 %S A278431 40,1609,57760,2116789,67971132,1796061464,39513263094,743248079740, %T A278431 12242795030458,179948822861856,2394561544941994,29174653111810701, %U A278431 328380943500399272,3439574456695348801,33729578625174035514 %N A278431 Number of nX3 0..3 arrays with rows and columns in lexicographic nondecreasing order but with exactly one mistake. %C A278431 Column 3 of A278435. %H A278431 R. H. Hardin, <a href="/A278431/b278431.txt">Table of n, a(n) for n = 1..210</a> %H A278431 R. H. Hardin, <a href="/A278431/a278431.txt">Empirical polynomial of degree 127</a> %F A278431 Empirical polynomial of degree 127 (see link above) %e A278431 Some solutions for n=3 %e A278431 ..0..1..1. .0..0..3. .3..0..2. .0..2..0. .2..2..3. .1..1..2. .0..3..3 %e A278431 ..3..0..3. .0..2..2. .3..1..2. .2..0..3. .0..2..1. .0..0..3. .3..1..3 %e A278431 ..1..3..1. .0..0..0. .3..3..2. .3..1..3. .3..1..1. .3..3..0. .2..3..3 %Y A278431 Cf. A278435. %K A278431 nonn %O A278431 1,1 %A A278431 _R. H. Hardin_, Nov 22 2016