A231241 Number of n X 3 0..3 arrays x(i,j) with each element horizontally, diagonally or antidiagonally next to at least one element with value (x(i,j)+1) mod 4, no adjacent elements equal, and upper left element zero.

0, 14, 78, 552, 3820, 26658, 185074, 1287036, 8947088, 62202118, 432432502, 3006318960, 20900215412, 145300370954, 1010142438650, 7022609687108, 48821873295640, 339414466598958, 2359642763446654, 16404468638111480

Offset

1,2

Comments

Column 3 of A231246.

Links

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

Formula

Empirical: a(n) = 4*a(n-1) +16*a(n-2) +26*a(n-3) +37*a(n-4) +6*a(n-5).

Empirical g.f.: 2*x^2*(7 + 11*x + 8*x^2) / (1 - 4*x - 16*x^2 - 26*x^3 - 37*x^4 - 6*x^5). - Colin Barker, Feb 09 2018

Example

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

Crossrefs

Sequence in context: A166842 A364770 A370960 * A138401 A099360 A329820

Adjacent sequences: A231238 A231239 A231240 * A231242 A231243 A231244

Keyword

nonn

Author

R. H. Hardin, Nov 06 2013

Status

approved