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 A223984 #6 Jul 23 2025 04:45:42 %S A223984 296,14751,308470,3770722,31831914,204647416,1067023886,4710529013, %T A223984 18159308422,62548820489,195900273940,565579629660,1521723229244, %U A223984 3849481958400,9222552207476,21052791564073,46024420537228 %N A223984 Number of nX5 0..3 arrays with rows unimodal and columns nondecreasing. %C A223984 Column 5 of A223987 %H A223984 R. H. Hardin, <a href="/A223984/b223984.txt">Table of n, a(n) for n = 1..210</a> %F A223984 Empirical: a(n) = (769/444787200)*n^15 + (781507/10897286400)*n^14 + (1419127/1037836800)*n^13 + (108727/6842880)*n^12 + (30122453/239500800)*n^11 + (15632539/21772800)*n^10 + (66446071/21772800)*n^9 + (299560531/30481920)*n^8 + (4868287/201600)*n^7 + (5624957/124416)*n^6 + (7644136631/119750400)*n^5 + (797122847/11975040)*n^4 + (85565105/1729728)*n^3 + (933168347/37837800)*n^2 + (73789/10010)*n + 1 %e A223984 Some solutions for n=3 %e A223984 ..0..0..0..0..1....1..2..2..2..1....0..2..0..0..0....0..0..1..1..0 %e A223984 ..0..1..1..2..1....1..2..3..3..1....1..2..1..0..0....0..0..1..2..0 %e A223984 ..0..1..2..3..1....2..3..3..3..2....2..3..2..1..0....2..3..3..3..2 %K A223984 nonn %O A223984 1,1 %A A223984 _R. H. Hardin_ Mar 30 2013