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 A223642 #6 Jul 23 2025 04:19:40 %S A223642 22,484,4904,28450,120307,428187,1370104,4063584,11337648,29980136, %T A223642 75501066,181755554,419574383,931417149,1993443114,4122964868, %U A223642 8258744026,16054980456,30348305906,55882034882,100405014805,176305599685 %N A223642 Number of nX6 0..1 arrays with rows, columns, diagonals and antidiagonals unimodal. %C A223642 Column 6 of A223644 %H A223642 R. H. Hardin, <a href="/A223642/b223642.txt">Table of n, a(n) for n = 1..210</a> %F A223642 Empirical: a(n) = (271/5443200)*n^12 - (5527/1995840)*n^11 + (55709/544320)*n^10 - (179285/72576)*n^9 + (69131681/1814400)*n^8 - (2290717/10080)*n^7 - (649163341/136080)*n^6 + (54977562187/362880)*n^5 - (2886586169891/1360800)*n^4 + (1624780719439/90720)*n^3 - (17508153293/189)*n^2 + (926735309999/3465)*n - 321893740 for n>13 %e A223642 Some solutions for n=4 %e A223642 ..0..1..1..1..1..1....0..0..0..0..1..1....0..0..0..1..0..0....0..1..0..0..0..0 %e A223642 ..1..1..1..1..1..1....0..1..1..1..1..1....1..1..1..1..1..0....1..1..1..1..0..0 %e A223642 ..1..1..1..1..1..1....0..1..1..1..1..1....0..0..1..1..1..1....0..1..1..1..0..0 %e A223642 ..0..0..0..1..1..0....0..0..0..0..0..0....0..0..0..0..1..0....0..1..1..0..0..0 %K A223642 nonn %O A223642 1,1 %A A223642 _R. H. Hardin_ Mar 24 2013