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 A253396 #6 Jul 23 2025 14:01:43 %S A253396 704,391,520,823,1269,1855,2726,3810,5311,7163,9569,12493,16140,20493, %T A253396 25773,31978,39346,47891,57867,69304,82472,97417,114425,133558,155118, %U A253396 179183,206071,235876,268932,305349,345477,389442,437610,490123,547363 %N A253396 Number of (n+1)X(7+1) 0..1 arrays with every 2X2 subblock antidiagonal maximum minus diagonal minimum nondecreasing horizontally and diagonal maximum minus antidiagonal minimum nondecreasing vertically. %C A253396 Column 7 of A253397 %H A253396 R. H. Hardin, <a href="/A253396/b253396.txt">Table of n, a(n) for n = 1..210</a> %F A253396 Empirical: a(n) = 4*a(n-1) -5*a(n-2) +5*a(n-4) -4*a(n-5) +a(n-6) for n>18 %F A253396 Empirical for n mod 2 = 0: a(n) = (1/3)*n^4 - (1/3)*n^3 + (337/6)*n^2 - (1423/6)*n + 914 for n>12 %F A253396 Empirical for n mod 2 = 1: a(n) = (1/3)*n^4 - (1/3)*n^3 + (337/6)*n^2 - (1423/6)*n + 943 for n>12 %e A253396 Some solutions for n=4 %e A253396 ..0..0..0..0..0..0..0..1....1..1..1..1..1..1..0..1....1..1..1..0..0..0..0..1 %e A253396 ..0..0..0..0..0..0..1..0....1..1..1..1..1..1..0..0....1..1..1..1..1..1..1..1 %e A253396 ..0..0..0..0..0..0..1..0....1..1..1..1..1..1..1..1....1..0..0..0..0..0..0..0 %e A253396 ..0..0..0..0..0..0..1..0....1..1..1..1..1..0..0..0....1..1..1..1..1..1..1..1 %e A253396 ..0..0..0..0..0..0..1..0....1..1..1..1..1..1..1..1....0..0..0..0..0..0..0..0 %K A253396 nonn %O A253396 1,1 %A A253396 _R. H. Hardin_, Dec 31 2014