A269882 Number of n X 2 0..5 arrays with some element plus some horizontally, diagonally, antidiagonally or vertically adjacent neighbor totalling five exactly once.

6, 432, 11280, 250992, 5125008, 99482544, 1867222224, 34216907760, 615877284624, 10931855797296, 191890772032848, 3337772595455088, 57618604390530960, 988280162421210288, 16858064726292134352, 286196732519053403376

Offset

1,1

Links

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

Formula

Empirical: a(n) = 30*a(n-1) - 197*a(n-2) - 420*a(n-3) - 196*a(n-4) for n>5.

Empirical g.f.: 6*x*(1 - x)^2*(1 + 44*x + 4*x^2) / (1 - 15*x - 14*x^2)^2. - Colin Barker, Jan 29 2019

Example

Some solutions for n=3:
..5..5. .1..1. .0..4. .1..2. .4..3. .3..3. .2..4. .4..2. .0..2. .1..4
..5..3. .3..2. .4..0. .2..1. .4..3. .1..0. .1..5. .4..5. .1..0. .3..3
..1..2. .4..5. .5..4. .3..0. .0..1. .2..3. .1..1. .3..2. .1..5. .3..4

Crossrefs

Column 2 of A269888.

Sequence in context: A370961 A275686 A173760 * A262013 A028665 A231316

Adjacent sequences: A269879 A269880 A269881 * A269883 A269884 A269885

Keyword

nonn

Author

R. H. Hardin, Mar 06 2016

Status

approved