A272966 Number of n X n 0..1 arrays with exactly n+n-2 having value 1 and no three 1's forming an isosceles triangle.

1, 6, 12, 8, 4, 8, 4, 8

Offset

1,2

Comments

Diagonal of A272973.

Links

Table of n, a(n) for n=1..8.

Example

Some solutions for n=3
..1..1..0. .1..0..1. .0..0..1. .0..1..1. .0..1..1. .1..0..0. .1..0..0
..0..0..0. .1..0..1. .1..0..1. .0..0..0. .0..0..0. .1..0..0. .1..0..1
..1..1..0. .0..0..0. .1..0..0. .0..1..1. .1..1..0. .0..1..1. .0..0..1

Crossrefs

Cf. A272973.

Sequence in context: A175365 A029769 A074590 * A105730 A213384 A005875

Adjacent sequences: A272963 A272964 A272965 * A272967 A272968 A272969

Keyword

nonn

Author

R. H. Hardin, May 11 2016

Status

approved