A275507 Number of 7 X n 0..2 arrays with no element equal to any value at offset (-2,-1) (-2,0) or (-1,-1) and new values introduced in order 0..2.

48, 200, 1168, 7140, 43780, 268152, 1643372, 10069540, 61703488, 378096660, 2316847540, 14196847960, 86993404476, 533065762516, 3266444015616, 20015648328132, 122649024958372, 751551142797496, 4605247533843404

Offset

1,1

Links

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

Formula

Empirical: a(n) = 3*a(n-1) + 18*a(n-2) + 11*a(n-3) - 23*a(n-4) - 4*a(n-5) for n>6.

Empirical g.f.: 4*x*(12 + 14*x - 74*x^2 - 123*x^3 + 60*x^4 + 59*x^5) / (1 - 3*x - 18*x^2 - 11*x^3 + 23*x^4 + 4*x^5). - Colin Barker, Feb 04 2019

Example

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

Crossrefs

Row 7 of A275504.

Sequence in context: A259245 A157923 A296367 * A072254 A290350 A260098

Adjacent sequences: A275504 A275505 A275506 * A275508 A275509 A275510

Keyword

nonn

Author

R. H. Hardin, Jul 30 2016

Status

approved