A277653 Number of n X 2 0..2 arrays with every element equal to some element at offset (-1,0) (-1,1) (0,-1) (0,1) or (1,0) both plus 1 mod 3 and minus 1 mod 3, with new values introduced in order 0..2.

0, 0, 1, 2, 8, 28, 98, 346, 1218, 4290, 15110, 53218, 187438, 660170, 2325166, 8189402, 28843662, 101589450, 357805342, 1260216122, 4438571726, 15632968522, 55060438334, 193926819802, 683024192622, 2405660280426, 8472908349854

Offset

1,4

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) - 2*a(n-4).

Empirical g.f.: x^3*(1 - x) / (1 - 3*x - 2*x^2 + 2*x^4). - Colin Barker, Feb 05 2019

Example

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

Crossrefs

Column 2 of A277659.

Sequence in context: A106731 A318010 A291383 * A066796 A104934 A056711

Adjacent sequences: A277650 A277651 A277652 * A277654 A277655 A277656

Keyword

nonn

Author

R. H. Hardin, Oct 26 2016

Status

approved