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 A278430 #5 Nov 22 2016 06:51:17 %S A278430 6,100,1609,19624,178352,1287838,7795151,41058743,193149285,826734193, %T A278430 3264405727,12016477160,41579224479,136142690453,424140541353, %U A278430 1263030700894,3609095743983,9929303441355,26377932553959,67838309686132 %N A278430 Number of nX2 0..3 arrays with rows and columns in lexicographic nondecreasing order but with exactly one mistake. %C A278430 Column 2 of A278435. %H A278430 R. H. Hardin, <a href="/A278430/b278430.txt">Table of n, a(n) for n = 1..210</a> %H A278430 R. H. Hardin, <a href="/A278430/a278430.txt">Empirical polynomial of degree 31</a> %F A278430 Empirical polynomial of degree 31 (see link above) %e A278430 Some solutions for n=4 %e A278430 ..0..0. .0..2. .0..3. .2..3. .0..1. .0..3. .0..1. .0..0. .1..2. .0..3 %e A278430 ..0..1. .2..1. .1..0. .1..2. .3..2. .3..1. .0..0. .1..3. .0..0. .3..0 %e A278430 ..3..3. .1..3. .3..3. .3..0. .1..2. .0..1. .0..1. .0..3. .2..2. .0..0 %e A278430 ..1..3. .3..1. .1..3. .3..2. .3..0. .3..2. .2..1. .3..1. .2..2. .0..3 %Y A278430 Cf. A278435. %K A278430 nonn %O A278430 1,1 %A A278430 _R. H. Hardin_, Nov 22 2016