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 A207095 #7 Jun 02 2025 07:40:12 %S A207095 4,10,26,68,176,458,1193,3103,8069,20982,54556,141854,368847,959072, %T A207095 2493770,6484280,16860367,43840173,113992823,296403114,770704718, %U A207095 2003979505,5210729566,13548892363,35229708616,91603972925,238187830252 %N A207095 Number of 0..3 arrays x(0..n-1) of n elements with each no smaller than the sum of its two previous neighbors modulo 4. %C A207095 Column 3 of A207100 %H A207095 R. H. Hardin, <a href="/A207095/b207095.txt">Table of n, a(n) for n = 1..210</a> %F A207095 Empirical: a(n) = 3*a(n-1) -a(n-2) +a(n-3) -3*a(n-4) +a(n-6) -2*a(n-9) +2*a(n-12) +a(n-13) -a(n-16) %e A207095 Some solutions for n=5 %e A207095 ..0....2....2....0....2....0....1....2....0....1....2....0....1....0....1....3 %e A207095 ..2....3....2....0....3....1....1....3....1....2....2....2....1....0....2....3 %e A207095 ..3....1....3....0....2....3....2....3....2....3....2....3....3....3....3....2 %e A207095 ..2....3....1....1....3....2....3....3....3....2....3....2....2....3....2....3 %e A207095 ..3....2....2....1....1....3....2....2....1....2....3....1....2....3....3....3 %K A207095 nonn %O A207095 1,1 %A A207095 _R. H. Hardin_ Feb 15 2012