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 A224058 #7 Jul 23 2025 04:58:47 %S A224058 16,160,984,4580,17723,59792,180821,499357,1276595,3053471,6892199, %T A224058 14784563,30317821,59727346,113515445,208880837,373286086,649594326, %U A224058 1103335758,1832822970,2983026931,4764357840,7477772697,11547960881 %N A224058 Number of nX2 0..3 arrays with rows, columns and antidiagonals unimodal and diagonals nondecreasing. %C A224058 Column 2 of A224064 %H A224058 R. H. Hardin, <a href="/A224058/b224058.txt">Table of n, a(n) for n = 1..210</a> %F A224058 Empirical: a(n) = (1/19160064)*n^12 + (1/456192)*n^11 + (2287/43545600)*n^10 + (215/290304)*n^9 + (2861/414720)*n^8 + (7187/161280)*n^7 + (10695901/43545600)*n^6 + (212027/207360)*n^5 + (6072841/2177280)*n^4 + (1652783/362880)*n^3 + (1059277/237600)*n^2 + (26023/13860)*n + 1 %e A224058 Some solutions for n=3 %e A224058 ..3..0....2..3....1..1....0..0....0..0....2..1....0..0....0..3....1..0....0..0 %e A224058 ..1..3....3..3....1..2....1..1....2..1....1..3....3..0....1..3....2..2....0..0 %e A224058 ..1..1....2..3....2..3....1..2....2..3....0..1....0..3....2..2....1..3....2..0 %K A224058 nonn %O A224058 1,1 %A A224058 _R. H. Hardin_ Mar 30 2013