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 A223983 #6 Jul 23 2025 04:45:26 %S A223983 130,3526,44803,358118,2086196,9647292,37395816,126087157,379654704, %T A223983 1040942916,2637614941,6248087300,13964013792,29662913488,60254807616, %U A223983 117633453657,221649696158,404535879938,717351048575,1239192239626 %N A223983 Number of nX4 0..3 arrays with rows unimodal and columns nondecreasing. %C A223983 Column 4 of A223987 %H A223983 R. H. Hardin, <a href="/A223983/b223983.txt">Table of n, a(n) for n = 1..210</a> %F A223983 Empirical: a(n) = (3551/47900160)*n^12 + (89357/39916800)*n^11 + (132341/4354560)*n^10 + (177787/725760)*n^9 + (1892753/1451520)*n^8 + (5834147/1209600)*n^7 + (11057083/870912)*n^6 + (17370313/725760)*n^5 + (6973385/217728)*n^4 + (26874943/907200)*n^3 + (186503/10395)*n^2 + (8831/1386)*n + 1 %e A223983 Some solutions for n=3 %e A223983 ..1..1..0..0....0..1..0..0....1..0..0..0....1..1..1..2....0..1..1..0 %e A223983 ..1..2..0..0....1..3..2..0....1..3..2..0....1..1..1..2....0..2..3..2 %e A223983 ..2..2..1..1....3..3..3..2....2..3..3..3....1..2..2..3....1..3..3..3 %K A223983 nonn %O A223983 1,1 %A A223983 _R. H. Hardin_ Mar 30 2013