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 A224260 #9 Mar 18 2025 22:32:53 %S A224260 148,4102,40182,240829,1122522,4480391,15921905,51343083,152072846, %T A224260 417672794,1072431538,2592681873,5938784236,12959932409,27074244297, %U A224260 54373767111,105367428574,197658533498,359961664018,638001956409,1103013543592,1863770039953,3083345640329 %N A224260 Number of n X 6 0..2 arrays with rows, diagonals and antidiagonals unimodal and columns nondecreasing. %H A224260 R. H. Hardin, <a href="/A224260/b224260.txt">Table of n, a(n) for n = 1..210</a> %F A224260 Empirical: a(n) = (761/8553600)*n^12 + (1733/3326400)*n^11 + (4339/388800)*n^10 + (1187/17280)*n^9 + (917087/1814400)*n^8 + (72307/25200)*n^7 + (1789211/194400)*n^6 + (1748533/24192)*n^5 + (3929747/97200)*n^4 + (7565567/21600)*n^3 - (359937251/415800)*n^2 - (7897829/2310)*n + 10655 for n>6. %e A224260 Some solutions for n=3: %e A224260 ..0..0..2..2..0..0....0..0..1..1..1..0....0..0..0..2..1..0....1..2..0..0..0..0 %e A224260 ..1..2..2..2..1..0....0..0..1..1..2..0....0..0..2..2..1..0....1..2..2..2..2..0 %e A224260 ..1..2..2..2..1..0....0..0..1..1..2..1....1..1..2..2..1..1....2..2..2..2..2..2 %Y A224260 Column 6 of A224262. %K A224260 nonn %O A224260 1,1 %A A224260 _R. H. Hardin_, Apr 02 2013 %E A224260 Name corrected by _Andrew Howroyd_, Mar 18 2025