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 A223643 #6 Jul 23 2025 04:19:47 %S A223643 29,841,10797,74599,354726,1370104,4682514,14767708,43862845, %T A223643 124004457,335617558,872372014,2182675327,5267049151,12280118231, %U A223643 27708360959,60600014150,128659653568,265553503693,533599565121,1045268782162 %N A223643 Number of nX7 0..1 arrays with rows, columns, diagonals and antidiagonals unimodal. %C A223643 Column 7 of A223644 %H A223643 R. H. Hardin, <a href="/A223643/b223643.txt">Table of n, a(n) for n = 1..78</a> %F A223643 Empirical: a(n) = (503/209563200)*n^14 - (185069/778377600)*n^13 + (1733819/119750400)*n^12 - (7176551/11975040)*n^11 + (36644381/2177280)*n^10 - (480531353/1814400)*n^9 - (76780811581/76204800)*n^8 + (29262582467/155520)*n^7 - (62420351374933/10886400)*n^6 + (281872655928541/2721600)*n^5 - (74234681724454753/59875200)*n^4 + (3261809312979967/332640)*n^3 - (557318597695013723/11642400)*n^2 + (14542780178794541/120120)*n - 90173668357 for n>19 %e A223643 Some solutions for n=4 %e A223643 ..0..0..0..1..1..0..0....0..1..1..0..0..0..0....0..0..1..0..0..0..0 %e A223643 ..0..0..1..1..1..1..1....0..1..1..1..1..1..0....0..1..1..1..1..1..1 %e A223643 ..0..1..1..1..1..1..0....0..0..0..1..1..1..0....1..1..1..1..1..1..0 %e A223643 ..0..0..0..0..1..0..0....0..0..0..0..0..0..1....0..0..0..0..1..0..0 %K A223643 nonn %O A223643 1,1 %A A223643 _R. H. Hardin_ Mar 24 2013