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 A223723 #6 Jul 23 2025 04:25:51 %S A223723 148,21904,1285547,38566854,733129227,9991366555,105179942478, %T A223723 899048082946,6467662339564,40225236084575,220829853370074, %U A223723 1087845990005427,4872987051273250,20066702492608999,76656800237546730 %N A223723 Number of nX6 0..2 arrays with rows, antidiagonals and columns unimodal. %C A223723 Column 6 of A223725 %H A223723 R. H. Hardin, <a href="/A223723/b223723.txt">Table of n, a(n) for n = 1..98</a> %F A223723 Empirical: a(n) = (114400861/793412278431252480000)*n^24 + (66282761/35608838483312640000)*n^23 + (140404438987/963429195237949440000)*n^22 + (1936103317/873349438832640000)*n^21 + (5962068639811/175168944588718080000)*n^20 + (4704445101737/4865804016353280000)*n^19 - (90703908587/1008373858652160000)*n^18 + (138127154730611/896332318801920000)*n^17 - (163329289577203/542318713896960000)*n^16 + (16908411747809/1464595292160000)*n^15 - (217368557681197651/2982752926433280000)*n^14 + (11820863509373563/15064408719360000)*n^13 + (257155619740709796619/41758540970065920000)*n^12 - (25420855801734316747/105450861035520000)*n^11 + (456374229168972649487/135579678474240000)*n^10 - (17588919370618913759/675967057920000)*n^9 + (3304860053076283198397/33894919618560000)*n^8 + (2999124386516753119073/16005934264320000)*n^7 - (9630627493426210141958447/2128789257154560000)*n^6 + (513812787405741819167581/19711011640320000)*n^5 - (356890305042110406199/4740986764800)*n^4 + (6260443467595336664171/82129215168000)*n^3 + (477210241388775897973/2151003254400)*n^2 - (16607355118655295/16997552)*n + 1358946210 for n>10 %e A223723 Some solutions for n=3 %e A223723 ..0..0..1..1..2..1....0..0..0..2..1..0....0..0..1..0..0..0....0..0..0..0..1..1 %e A223723 ..0..0..0..1..1..2....0..1..2..1..1..0....0..1..2..2..2..0....0..1..2..2..2..0 %e A223723 ..0..0..0..2..1..0....0..0..0..1..2..2....0..0..0..1..0..0....0..0..0..2..1..0 %K A223723 nonn %O A223723 1,1 %A A223723 _R. H. Hardin_ Mar 26 2013