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 A268954 #4 Feb 16 2016 11:49:56 %S A268954 1,2,4,12,40,154,656,3073,15579,84572,485726,2918103,18146537, %T A268954 115772922,752410412,4954432229,32923518967,220172576536, %U A268954 1478770322954,9961340359315,67235635905765,454423768826774,3074025717951560 %N A268954 Number of length-n 0..6 arrays with no repeated value equal to the previous repeated value, with new values introduced in sequential order. %C A268954 Column 6 of A268956. %H A268954 R. H. Hardin, <a href="/A268954/b268954.txt">Table of n, a(n) for n = 1..210</a> %F A268954 Empirical: a(n) = 27*a(n-1) -280*a(n-2) +1258*a(n-3) -781*a(n-4) -13833*a(n-5) +39878*a(n-6) +32104*a(n-7) -261136*a(n-8) +111564*a(n-9) +754544*a(n-10) -663920*a(n-11) -1052352*a(n-12) +1135872*a(n-13) +580608*a(n-14) -663552*a(n-15) for n>17 %e A268954 Some solutions for n=8 %e A268954 ..0. .0. .0. .0. .0. .0. .0. .0. .0. .0. .0. .0. .0. .0. .0. .0 %e A268954 ..1. .1. .1. .1. .1. .0. .0. .1. .1. .1. .1. .1. .1. .1. .1. .1 %e A268954 ..2. .2. .2. .0. .2. .1. .1. .2. .2. .2. .2. .0. .2. .2. .2. .2 %e A268954 ..3. .0. .3. .1. .3. .0. .2. .3. .3. .3. .1. .2. .1. .2. .0. .3 %e A268954 ..2. .2. .0. .2. .4. .1. .1. .0. .2. .3. .3. .1. .2. .1. .3. .4 %e A268954 ..3. .3. .1. .3. .0. .2. .0. .1. .1. .0. .1. .3. .3. .0. .4. .2 %e A268954 ..3. .0. .3. .1. .5. .3. .2. .3. .3. .0. .2. .2. .2. .1. .3. .1 %e A268954 ..4. .0. .0. .1. .0. .2. .3. .1. .1. .3. .3. .2. .2. .2. .4. .4 %Y A268954 Cf. A268956. %K A268954 nonn %O A268954 1,2 %A A268954 _R. H. Hardin_, Feb 16 2016