cp's OEIS Frontend

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.

A188820 Number of n X 5 binary arrays without the pattern 0 1 diagonally or antidiagonally.

Original entry on oeis.org

32, 169, 432, 841, 1360, 2025, 2800, 3721, 4752, 5929, 7216, 8649, 10192, 11881, 13680, 15625, 17680, 19881, 22192, 24649, 27216, 29929, 32752, 35721, 38800, 42025, 45360, 48841, 52432, 56169, 60016, 64009, 68112, 72361, 76720, 81225, 85840, 90601
Offset: 1

Views

Author

R. H. Hardin, Apr 11 2011

Keywords

Comments

Column 5 of A188824.

Examples

			Some solutions for 3 X 5:
..1..1..1..1..0....1..1..1..1..1....0..1..0..1..1....0..1..1..1..1
..0..1..1..0..1....0..1..1..1..0....0..0..0..0..1....1..0..1..1..1
..1..0..0..1..0....1..0..0..0..0....0..0..0..0..0....0..1..0..0..0
		

Crossrefs

Cf. A188824.

Formula

Empirical: a(n) = 2*a(n-1) - 2*a(n-3) + a(n-4) for n>5.
Conjectures from Colin Barker, Apr 29 2018: (Start)
G.f.: x*(32 + 105*x + 94*x^2 + 41*x^3 - 16*x^4) / ((1 - x)^3*(1 + x)).
a(n) = 9 - 48*n + 64*n^2 for n even.
a(n) = -48*n + 64*n^2 for n>1 and odd.
(End)