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 A223641 #6 Jul 23 2025 04:19:34 %S A223641 16,256,2014,9808,36947,120307,354726,967582,2469396,5941152,13555296, %T A223641 29475566,61346859,122671803,236477826,440811016,796753648,1399853788, %U A223641 2396080742,4003682172,6542620323,10473608867,16449161244,25379498938 %N A223641 Number of nX5 0..1 arrays with rows, columns, diagonals and antidiagonals unimodal. %C A223641 Column 5 of A223644 %H A223641 R. H. Hardin, <a href="/A223641/b223641.txt">Table of n, a(n) for n = 1..210</a> %F A223641 Empirical: a(n) = (359/453600)*n^10 - (391/18144)*n^9 + (27901/60480)*n^8 - (5318/945)*n^7 + (220373/5400)*n^6 + (42079/4320)*n^5 - (611182913/181440)*n^4 + (204761033/5670)*n^3 - (1618325179/8400)*n^2 + (680702213/1260)*n - 629380 for n>7 %e A223641 Some solutions for n=4 %e A223641 ..0..0..1..0..0....0..0..1..1..0....1..1..1..1..1....0..1..0..0..0 %e A223641 ..0..1..1..1..0....0..0..1..1..1....1..1..1..1..1....0..1..0..0..0 %e A223641 ..0..0..1..1..1....0..0..1..1..0....0..1..1..1..1....1..0..0..0..0 %e A223641 ..0..0..1..0..0....0..0..1..1..0....0..0..1..0..0....1..0..0..0..0 %K A223641 nonn %O A223641 1,1 %A A223641 _R. H. Hardin_ Mar 24 2013