A272951 Number of n X n 0..1 arrays with exactly n+n-2 having value 1 and no three 1's forming an isosceles right triangle.

1, 6, 24, 60, 768, 7468, 131056, 4614732

Offset

1,2

Comments

Diagonal of A272958.

Links

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

Example

Some solutions for n=5
..0..0..0..0..1. .1..0..1..0..0. .1..0..1..1..0. .0..1..0..0..1
..1..0..0..0..0. .1..0..0..0..1. .0..0..0..0..1. .0..0..0..0..1
..1..0..0..1..1. .0..0..0..0..0. .0..0..0..0..0. .0..0..0..0..1
..1..0..0..0..0. .1..0..0..0..1. .0..1..0..0..1. .0..0..1..1..0
..0..1..0..0..1. .1..0..1..0..0. .0..0..1..1..0. .1..1..0..0..0

Crossrefs

Cf. A272958.

Sequence in context: A371175 A292889 A366546 * A358081 A371045 A371159

Adjacent sequences: A272948 A272949 A272950 * A272952 A272953 A272954

Keyword

nonn

Author

R. H. Hardin, May 11 2016

Status

approved