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 A217953 #6 Jul 22 2025 23:43:59 %S A217953 4,16,50,130,296,610,1163,2083,3558,5902,9734,16410,28969,54049, %T A217953 105529,211097,423650,840654,1636964,3121556,5839194,10760322, %U A217953 19647966,35780070,65376302,120393728,223926347,420463887,795087960,1508967508,2864523898 %N A217953 Number of n element 0..3 arrays with each element the minimum of 7 adjacent elements of a random 0..3 array of n+6 elements. %C A217953 Column 7 of A217954 %H A217953 R. H. Hardin, <a href="/A217953/b217953.txt">Table of n, a(n) for n = 1..210</a> %F A217953 Empirical: a(n) = 4*a(n-1) -6*a(n-2) +4*a(n-3) -a(n-4) +6*a(n-8) -4*a(n-9) +6*a(n-10) +4*a(n-11) +5*a(n-12) +6*a(n-13) +7*a(n-14) +8*a(n-15) +4*a(n-16) +6*a(n-17) +5*a(n-18) +4*a(n-19) +3*a(n-20) +2*a(n-21) +a(n-22) %e A217953 Some solutions for n=4 %e A217953 ..3....2....0....3....1....0....1....1....1....0....1....0....1....0....1....3 %e A217953 ..2....2....3....1....3....1....1....1....3....1....2....3....3....2....2....3 %e A217953 ..1....2....2....0....2....2....0....3....2....2....3....2....0....3....1....3 %e A217953 ..1....1....1....0....2....2....0....3....1....0....3....2....0....3....1....3 %K A217953 nonn %O A217953 1,1 %A A217953 _R. H. Hardin_ Oct 15 2012