A268901 Number of n X 5 0..2 arrays with some element plus some horizontally or antidiagonally adjacent neighbor totalling two exactly once.

96, 2664, 54936, 1004184, 17194680, 282550680, 4513169016, 70609114584, 1087342615224, 16536864398616, 248976164499192, 3717450986032728, 55118358414612792, 812385229848253848, 11912420604393611640

Offset

1,1

Links

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

Formula

Empirical: a(n) = 30*a(n-1) - 261*a(n-2) + 540*a(n-3) - 324*a(n-4).

Empirical g.f.: 24*x*(4 - 9*x + 3*x^2 - 18*x^3) / (1 - 15*x + 18*x^2)^2. - Colin Barker, Jan 16 2019

Example

Some solutions for n=3:
..1..2..2..1..2. .2..2..1..0..1. .2..1..0..1..2. .0..1..2..2..1
..2..2..2..1..0. .2..0..1..0..1. .2..1..0..0..0. .0..1..2..1..0
..2..2..0..0..0. .1..0..1..0..0. .0..1..0..0..0. .2..2..2..1..0

Crossrefs

Column 5 of A268904.

Sequence in context: A090449 A336677 A233709 * A239158 A105254 A234075

Adjacent sequences: A268898 A268899 A268900 * A268902 A268903 A268904

Keyword

nonn

Author

R. H. Hardin, Feb 15 2016

Status

approved