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 A223671 #6 Jul 23 2025 04:22:29 %S A223671 16,256,1723,6454,18980,49561,119150,267643,567197,1142224,2198273, %T A223671 4062420,7238132,12477929,20877528,33995513,54002935,83867606, %U A223671 127578211,190413722,279263958,403007495,572953490,803354343,1111996481,1520876908 %N A223671 Number of 4Xn 0..1 arrays with rows, diagonals and antidiagonals unimodal. %C A223671 Row 4 of A223669 %H A223671 R. H. Hardin, <a href="/A223671/b223671.txt">Table of n, a(n) for n = 1..210</a> %F A223671 Empirical: a(n) = (1/112)*n^8 - (19/210)*n^7 + (59/45)*n^6 - (61/120)*n^5 - (8789/144)*n^4 + (99083/120)*n^3 - (10598579/2520)*n^2 + (1548737/140)*n - 11539 for n>6 %e A223671 Some solutions for n=4 %e A223671 ..1..0..0..0....0..1..1..0....0..0..0..0....0..1..1..1....0..0..0..1 %e A223671 ..0..1..0..0....0..0..0..0....1..1..0..0....0..1..1..0....0..1..1..0 %e A223671 ..0..1..1..1....0..1..0..0....0..0..1..1....1..1..1..0....1..0..0..0 %e A223671 ..1..0..0..0....0..0..1..0....0..0..0..0....0..1..1..0....0..0..1..0 %K A223671 nonn %O A223671 1,1 %A A223671 _R. H. Hardin_ Mar 25 2013