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 A268958 #4 Feb 16 2016 11:53:19 %S A268958 7,77,499,2785,15124,84572,497262,3090688,20283861,140149935, %T A268958 1016257437,7710982245,61062373842,503482366796,4313580692976, %U A268958 38328590354914,352618807539531,3353663977065151,32927374589832727,333319732348780989 %N A268958 Number of length-(n+4) 0..n arrays with no repeated value equal to the previous repeated value, with new values introduced in sequential order. %C A268958 Subdiagonal 4 of A268956. %H A268958 R. H. Hardin, <a href="/A268958/b268958.txt">Table of n, a(n) for n = 1..118</a> %e A268958 Some solutions for n=6 %e A268958 ..0. .0. .0. .0. .0. .0. .0. .0. .0. .0. .0. .0. .0. .0. .0. .0 %e A268958 ..1. .0. .0. .1. .1. .1. .1. .1. .1. .1. .1. .1. .1. .1. .1. .1 %e A268958 ..2. .1. .1. .2. .2. .1. .2. .1. .2. .2. .2. .2. .2. .0. .0. .2 %e A268958 ..3. .2. .2. .2. .2. .0. .2. .2. .1. .0. .3. .0. .0. .0. .1. .0 %e A268958 ..1. .0. .3. .3. .0. .2. .1. .3. .2. .1. .4. .1. .2. .2. .2. .3 %e A268958 ..1. .1. .2. .2. .3. .3. .1. .1. .3. .3. .2. .3. .0. .3. .0. .3 %e A268958 ..3. .3. .1. .0. .1. .1. .0. .0. .2. .0. .0. .3. .0. .2. .1. .1 %e A268958 ..2. .4. .1. .3. .4. .2. .2. .1. .2. .2. .4. .2. .3. .3. .1. .0 %e A268958 ..0. .3. .2. .0. .0. .4. .2. .2. .3. .2. .0. .0. .2. .4. .3. .4 %e A268958 ..1. .5. .1. .4. .0. .1. .3. .2. .4. .3. .2. .4. .2. .5. .2. .2 %Y A268958 Cf. A268956. %K A268958 nonn %O A268958 1,1 %A A268958 _R. H. Hardin_, Feb 16 2016