A281470 Number of 2Xn 0..1 arrays with no element equal to more than two of its horizontal, diagonal or antidiagonal neighbors and with new values introduced in order 0 sequentially upwards.

2, 8, 17, 37, 78, 169, 361, 778, 1673, 3605, 7774, 16777, 36241, 78338, 169465, 366829, 794550, 1721977, 3733929, 8100666, 17582281, 38178181, 82932878, 180217513, 391754433, 851856306, 1852865241, 4031221917, 8772754342, 19095598617

Offset

1,1

Comments

Row 2 of A281469.

Links

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

Formula

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

Empirical g.f.: 2*x -x^2*(8-7*x-22*x^2-2*x^3+16*x^4) /(2*x-1) /(2*x^4-3*x^2-x+1) . - R. J. Mathar, May 14 2017

Example

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

Crossrefs

Cf. A281469.

Sequence in context: A294548 A061150 A160189 * A295147 A215933 A328742

Adjacent sequences: A281467 A281468 A281469 * A281471 A281472 A281473

Keyword

nonn

Author

R. H. Hardin, Jan 22 2017

Status

approved