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 A224052 #6 Jul 23 2025 04:58:11 %S A224052 22,218,1232,5219,18502,57911,164781,433762,1068664,2485274,5492414, %T A224052 11598655,23514508,45950300,86850332,159256653,284063565,494009870, %U A224052 839363352,1395884951,2275822878,3642884361,5732370123,8877939920 %N A224052 Number of nX3 0..2 arrays with rows and columns unimodal and antidiagonals nondecreasing. %C A224052 Column 3 of A224057 %H A224052 R. H. Hardin, <a href="/A224052/b224052.txt">Table of n, a(n) for n = 1..210</a> %F A224052 Empirical: a(n) = (1/19160064)*n^12 + (5/3193344)*n^11 + (1627/43545600)*n^10 + (751/1451520)*n^9 + (3247/580608)*n^8 + (18607/483840)*n^7 + (11286841/43545600)*n^6 + (1893037/1451520)*n^5 + (2032151/435456)*n^4 + (1618571/362880)*n^3 + (7125527/831600)*n^2 + (241067/27720)*n - 9 for n>1 %e A224052 Some solutions for n=3 %e A224052 ..0..1..0....2..1..0....1..0..0....0..0..0....1..2..1....2..1..0....0..0..0 %e A224052 ..2..1..0....2..2..1....1..1..0....0..0..1....2..2..0....2..0..0....1..2..0 %e A224052 ..1..1..2....2..2..1....2..1..1....2..2..2....2..1..0....1..0..0....2..1..0 %K A224052 nonn %O A224052 1,1 %A A224052 _R. H. Hardin_ Mar 30 2013