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 A235674 #6 Jul 23 2025 08:43:48 %S A235674 208,2456,28584,330840,3824528,44196144,510685176,5900818062, %T A235674 68181837738,787815537064,9102909355490,105180650740834, %U A235674 1215322331681740,14042586259073748,162256730906114932,1874814669334245592 %N A235674 Number of (n+1)X(3+1) 0..1 arrays with the difference between each 2X2 subblock maximum and minimum lexicographically nondecreasing columnwise and nonincreasing rowwise. %C A235674 Column 3 of A235679 %H A235674 R. H. Hardin, <a href="/A235674/b235674.txt">Table of n, a(n) for n = 1..210</a> %F A235674 Empirical: a(n) = 13*a(n-1) -7*a(n-2) -120*a(n-3) +60*a(n-4) +376*a(n-5) -111*a(n-6) -477*a(n-7) +47*a(n-8) +216*a(n-9) +20*a(n-10) -16*a(n-11) %e A235674 Some solutions for n=3 %e A235674 ..1..0..1..0....0..1..1..1....1..1..0..1....0..0..1..1....0..1..0..1 %e A235674 ..1..0..0..0....0..1..0..1....0..0..1..0....1..0..0..0....1..1..1..0 %e A235674 ..0..1..0..1....0..0..1..1....0..1..1..1....1..0..1..1....0..1..0..1 %e A235674 ..0..1..1..1....0..0..0..1....1..0..1..0....1..1..0..1....1..0..0..0 %K A235674 nonn %O A235674 1,1 %A A235674 _R. H. Hardin_, Jan 13 2014