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 A223808 #6 Jul 23 2025 04:32:56 %S A223808 130,16900,825896,20847008,342521725,4146732319,39816673636, %T A223808 317796753758,2176384736806,13081738670880,70201100137308, %U A223808 340874317119700,1514107865155566,6208541401894070,23684173752732531,84617914222910737 %N A223808 Number of nX4 0..3 arrays with rows, columns, diagonals and antidiagonals unimodal. %C A223808 Column 4 of A223811 %H A223808 R. H. Hardin, <a href="/A223808/b223808.txt">Table of n, a(n) for n = 1..210</a> %F A223808 Empirical: a(n) = (1224989653/34469355651846635520000)*n^24 + (9790897789/8617338912961658880000)*n^23 + (17368054339/449600291111043072000)*n^22 + (6343785587/8515157028618240000)*n^21 + (742042863307/58389648196239360000)*n^20 + (874268046919/4865804016353280000)*n^19 + (340257615613/179266463760384000)*n^18 + (9655773652423/448166159400960000)*n^17 + (216017366507863/1265410332426240000)*n^16 + (127305463223041/105450861035520000)*n^15 + (2176033515218659/198850195095552000)*n^14 + (1092716136330817/41427123978240000)*n^13 + (121113866805425089/515537542840320000)*n^12 + (342583305621940841/105450861035520000)*n^11 - (2450919674438782711/63270516621312000)*n^10 + (11061596378517660259/26362715258880000)*n^9 - (547858838894740099247/192071211171840000)*n^8 + (217452379672611043021/16005934264320000)*n^7 - (15434864255601855529021/425757851430912000)*n^6 - (981113327920619121617/59133034920960000)*n^5 + (97554150097562928884627/162615846032640000)*n^4 - (2213625571607144902901/903421366848000)*n^3 + (32215709819070912077/7420961227680)*n^2 - (118869402789119/74364290)*n - 3422935 for n>8 %e A223808 Some solutions for n=3 %e A223808 ..0..0..2..3....0..0..3..0....0..1..2..0....0..0..3..0....1..1..1..2 %e A223808 ..0..1..1..3....0..2..3..0....1..2..2..2....0..1..3..2....1..2..2..2 %e A223808 ..0..0..1..1....1..1..1..3....0..0..3..0....0..3..3..2....0..3..3..1 %K A223808 nonn %O A223808 1,1 %A A223808 _R. H. Hardin_ Mar 27 2013