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 A221571 #8 Jun 02 2025 08:21:44 %S A221571 0,37,197,1369,8991,59705,395641,2622817,17385993,115249117,763966685, %T A221571 5064207645,33569783613,222528473325,1475103973253,9778217146445, %U A221571 64818163521317,429668748357261,2848202159470085,18880255015594493 %N A221571 Number of 0..6 arrays of length n with each element differing from at least one neighbor by something other than 1. %C A221571 Column 6 of A221573 %H A221571 R. H. Hardin, <a href="/A221571/b221571.txt">Table of n, a(n) for n = 1..210</a> %F A221571 Empirical: a(n) = 7*a(n-1) -4*a(n-2) +6*a(n-3) +26*a(n-4) +10*a(n-5) +16*a(n-6) +12*a(n-8). %F A221571 Empirical: -x^2*(37-62*x+138*x^2-26*x^3+100*x^4-36*x^5+48*x^6) / ( -1+7*x-4*x^2+6*x^3+26*x^4+10*x^5+16*x^6+12*x^8 ). - _R. J. Mathar_, Jun 06 2013 %e A221571 Some solutions for n=6 %e A221571 ..4....2....5....0....4....4....2....3....1....3....6....0....5....4....0....2 %e A221571 ..6....5....1....2....4....6....5....5....4....1....6....2....0....6....6....2 %e A221571 ..2....5....6....5....5....2....2....5....1....0....2....3....0....5....1....5 %e A221571 ..4....4....6....2....3....3....5....6....1....0....6....1....6....1....5....1 %e A221571 ..6....2....0....5....4....1....1....6....1....0....0....3....4....3....5....4 %e A221571 ..6....4....2....5....1....5....6....4....4....4....4....0....2....3....3....2 %K A221571 nonn %O A221571 1,2 %A A221571 _R. H. Hardin_ Jan 20 2013