A207145 Number of (n+1) X 5 0..2 arrays with every 2 X 2 subblock having nonzero determinant and commuting with every horizontal or vertical neighbor.

62, 95, 110, 190, 218, 374, 434, 742, 866, 1478, 1730, 2954, 3458, 5906, 6914, 11810, 13826, 23618, 27650, 47234, 55298, 94466, 110594, 188930, 221186, 377858, 442370, 755714, 884738, 1511426, 1769474, 3022850, 3538946, 6045698, 7077890, 12091394

Offset

1,1

Comments

Column 4 of A207149.

Links

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

Formula

Empirical: a(n) = a(n-1) + 2*a(n-2) - 2*a(n-3) for n>11.

Empirical g.f.: x*(62 + 33*x - 109*x^2 + 14*x^3 - 2*x^4 - 4*x^5 + 4*x^6 - 4*x^7 + 4*x^8 - 4*x^9 + 4*x^10) / ((1 - x)*(1 - 2*x^2)). - Colin Barker, Jun 19 2018

Example

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

Crossrefs

Cf. A207149.

Sequence in context: A114966 A104078 A136774 * A044249 A044630 A103584

Adjacent sequences: A207142 A207143 A207144 * A207146 A207147 A207148

Keyword

nonn

Author

R. H. Hardin, Feb 15 2012

Status

approved