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 A269612 #5 Mar 01 2016 14:52:06 %S A269612 2,9,64,612,7440,110099,1923796,38800210,887591878,22714070251, %T A269612 643030722208,19954247152834,673552866591198,24570545121277999, %U A269612 963253518328620796,40387590591059009524,1803427358679591518028 %N A269612 Number of length-n 0..n arrays with no repeated value differing from the previous repeated value by other than plus two, zero or minus 1. %C A269612 Diagonal of A269619. %H A269612 R. H. Hardin, <a href="/A269612/b269612.txt">Table of n, a(n) for n = 1..210</a> %e A269612 Some solutions for n=6 %e A269612 ..5. .1. .4. .0. .0. .5. .0. .1. .2. .0. .0. .1. .2. .6. .1. .6 %e A269612 ..0. .3. .6. .0. .3. .1. .6. .0. .1. .2. .2. .2. .0. .2. .3. .4 %e A269612 ..6. .5. .1. .4. .6. .1. .6. .6. .4. .5. .5. .2. .1. .0. .4. .2 %e A269612 ..1. .2. .0. .1. .1. .1. .2. .0. .4. .1. .6. .4. .6. .1. .3. .3 %e A269612 ..6. .2. .1. .5. .3. .6. .3. .4. .4. .0. .2. .0. .0. .0. .2. .4 %e A269612 ..1. .5. .1. .6. .0. .1. .2. .2. .6. .6. .1. .5. .6. .4. .2. .4 %Y A269612 Cf. A269619. %K A269612 nonn %O A269612 1,1 %A A269612 _R. H. Hardin_, Mar 01 2016