A275132 Number of 3 X n 0..2 arrays with no element equal to any value at offset (-2,-2) (-1,0) or (-1,1) and new values introduced in order 0..2.

2, 12, 45, 174, 675, 2607, 10077, 38967, 150651, 582435, 2251827, 8706015, 33659139, 130132935, 503119779, 1945160703, 7520376939, 29075268471, 112410752211, 434602254687, 1680258482619, 6496212425799, 25115645192451, 97102063806447

Offset

1,1

Links

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

Formula

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

Empirical g.f.: x*(2 + 6*x + 5*x^2 + 3*x^3 - 5*x^4 - 4*x^5) / ((1 + x + 2*x^2)*(1 - 4*x + 2*x^3)). - Colin Barker, Jan 31 2019

Example

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

Crossrefs

Row 3 of A275131.

Sequence in context: A371487 A356868 A267344 * A276294 A066258 A123771

Adjacent sequences: A275129 A275130 A275131 * A275133 A275134 A275135

Keyword

nonn

Author

R. H. Hardin, Jul 17 2016

Status

approved