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 A223683 #6 Jul 23 2025 04:23:33 %S A223683 32,1024,13045,85663,384009,1363639,4123210,11062778,27036251, %T A223683 61267043,130398069,263173867,507406703,940062881,1681523014, %U A223683 2915323586,4914979621,8079822545,12982166253,20428540847,31538210365,47842720947 %N A223683 Number of 5Xn 0..1 arrays with rows and antidiagonals unimodal. %C A223683 Row 5 of A223680 %H A223683 R. H. Hardin, <a href="/A223683/b223683.txt">Table of n, a(n) for n = 1..210</a> %F A223683 Empirical: a(n) = (359/453600)*n^10 + (251/30240)*n^9 + (14533/60480)*n^8 + (583/630)*n^7 + (62303/5400)*n^6 - (4999/1440)*n^5 + (14868751/181440)*n^4 - (1038043/3780)*n^3 + (3156491/8400)*n^2 - (91003/210)*n + 362 for n>2 %e A223683 Some solutions for n=3 %e A223683 ..0..0..0....0..1..0....1..1..1....0..1..1....1..0..0....1..1..1....1..0..0 %e A223683 ..0..0..0....0..0..0....1..1..1....0..1..0....1..1..0....0..0..0....0..0..0 %e A223683 ..0..1..0....0..0..0....0..1..0....0..1..1....0..1..0....0..0..0....0..1..0 %e A223683 ..0..1..0....0..0..1....0..0..0....1..1..0....0..0..0....0..0..1....0..0..1 %e A223683 ..0..1..1....1..1..0....0..1..0....0..0..1....0..1..1....0..0..0....0..1..1 %K A223683 nonn %O A223683 1,1 %A A223683 _R. H. Hardin_ Mar 25 2013