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 A217951 #7 Jul 22 2025 23:43:46 %S A217951 4,16,50,130,296,610,1177,2209,4202,8366,17569,38251,84134,183334, %T A217951 392284,824110,1708779,3523509,7276452,15117730,31635969,66571659, %U A217951 140445543,296202061,623355780,1308333724,2740013491,5731815041,11989696656 %N A217951 Number of n element 0..3 arrays with each element the minimum of 5 adjacent elements of a random 0..3 array of n+4 elements. %C A217951 Column 5 of A217954 %H A217951 R. H. Hardin, <a href="/A217951/b217951.txt">Table of n, a(n) for n = 1..210</a> %F A217951 Empirical: a(n) = 4*a(n-1) -6*a(n-2) +4*a(n-3) -a(n-4) +6*a(n-6) -4*a(n-7) +6*a(n-8) +4*a(n-9) +5*a(n-10) +6*a(n-11) +2*a(n-12) +4*a(n-13) +3*a(n-14) +2*a(n-15) +a(n-16) %e A217951 Some solutions for n=4 %e A217951 ..1....0....2....2....1....2....2....1....3....0....0....2....1....0....1....0 %e A217951 ..0....0....2....3....1....2....3....1....3....2....0....1....2....2....2....3 %e A217951 ..0....3....3....2....2....1....1....3....3....0....3....1....2....1....2....3 %e A217951 ..0....3....0....1....1....1....0....0....1....0....2....0....1....0....0....1 %K A217951 nonn %O A217951 1,1 %A A217951 _R. H. Hardin_ Oct 15 2012