A272954 Number of nX4 0..1 arrays with exactly n+4-2 having value 1 and no three 1s forming an isosceles right triangle.

4, 21, 24, 60, 210, 637, 1840, 5792, 18556, 54034, 160246, 499140, 1501706, 4627363, 13954490, 43064736, 131174878, 399170874, 1222825766, 3739040310, 11456400210, 35068696769, 107362206600, 329271410590, 1009129910706, 3096269613087

Offset

1,1

Comments

Column 4 of A272958.

Links

R. H. Hardin, Table of n, a(n) for n = 1..110

Example

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

Crossrefs

Cf. A272958.

Sequence in context: A138228 A303722 A305225 * A133784 A041821 A042429

Adjacent sequences: A272951 A272952 A272953 * A272955 A272956 A272957

Keyword

nonn

Author

R. H. Hardin, May 11 2016

Status

approved