A280435 Number of nX3 0..1 arrays with no element equal to more than one of its horizontal and vertical neighbors, with the exception of exactly one element, and with new values introduced in order 0 sequentially upwards.

1, 10, 21, 42, 77, 136, 236, 404, 687, 1162, 1959, 3294, 5528, 9262, 15497, 25898, 43233, 72100, 120132, 199992, 332675, 552970, 918491, 1524602, 2529072, 4192786, 6946941, 11503914, 19040117, 31497472, 52080284, 86073884, 142192983

Offset

1,2

Comments

Column 3 of A280440.

Links

R. H. Hardin, Table of n, a(n) for n = 1..210

Formula

Empirical: a(n) = 3*a(n-1) -a(n-2) -3*a(n-3) +a(n-4) +a(n-5) for n>6.

Empirical g.f.: x -x^2*(10-9*x-11*x^2+2*x^3) / ( (x-1)*(x^2+x-1)^2 ). - R. J. Mathar, Jan 04 2017

Example

Some solutions for n=4
..0..0..1. .0..1..0. .0..0..1. .0..1..0. .0..1..0. .0..1..0. .0..1..0
..1..1..0. .1..1..1. .0..1..0. .1..0..1. .1..0..0. .0..1..0. .1..0..1
..0..0..1. .0..1..0. .1..0..1. .0..1..0. .0..1..0. .1..0..1. .1..1..0
..1..0..1. .1..0..1. .1..0..1. .0..1..1. .1..0..1. .0..0..1. .1..0..1

Crossrefs

Cf. A280440.

Sequence in context: A256884 A089584 A192743 * A095824 A086225 A240994

Adjacent sequences: A280432 A280433 A280434 * A280436 A280437 A280438

Keyword

nonn

Author

R. H. Hardin, Jan 03 2017

Status

approved