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 A250765 #8 Nov 18 2018 09:09:20 %S A250765 68,114,196,350,648,1234,2396,4710,9328,18554,36996,73870,147608, %T A250765 295074,589996,1179830,2359488,4718794,9437396,18874590,37748968, %U A250765 75497714,150995196,301990150,603980048,1207959834,2415919396,4831838510 %N A250765 Number of (n+1) X (4+1) 0..1 arrays with nondecreasing x(i,j)-x(i,j-1) in the i direction and nondecreasing absolute value of x(i,j)-x(i-1,j) in the j direction. %H A250765 R. H. Hardin, <a href="/A250765/b250765.txt">Table of n, a(n) for n = 1..210</a> %F A250765 Empirical: a(n) = 4*a(n-1) - 5*a(n-2) + 2*a(n-3); a(n) = 36*2^(n-1) + 10*n + 22. %F A250765 Empirical g.f.: 2*x*(34 - 79*x + 40*x^2) / ((1 - x)^2*(1 - 2*x)). - _Colin Barker_, Nov 18 2018 %e A250765 Some solutions for n=4: %e A250765 ..1..1..0..0..0....1..1..1..1..0....1..1..1..1..1....1..0..1..0..0 %e A250765 ..1..1..0..0..0....1..1..1..1..0....0..0..0..0..0....1..0..1..0..0 %e A250765 ..1..1..1..1..1....1..1..1..1..0....0..0..0..0..0....1..0..1..0..0 %e A250765 ..1..1..1..1..1....1..1..1..1..0....0..0..0..0..0....1..0..1..0..1 %e A250765 ..1..1..1..1..1....1..1..1..1..0....1..1..1..1..1....1..0..1..0..1 %Y A250765 Column 4 of A250769. %K A250765 nonn %O A250765 1,1 %A A250765 _R. H. Hardin_, Nov 27 2014