A251144 Number of (n+1) X (3+1) 0..2 arrays with every 2 X 2 subblock summing to 4 and no 2 X 2 subblock having exactly two nonzero entries.

53, 87, 143, 247, 433, 777, 1413, 2607, 4863, 9167, 17433, 33417, 64493, 125207, 244303, 478727, 941473, 1857097, 3672373, 7277087, 14444703, 28712287, 57137993, 113812297, 226874333, 452534727, 903105263, 1803032407, 3600922513

Offset: 1

Author

R. H. Hardin, Nov 30 2014

Keywords

• nonn

Examples

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

Links

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

Crossrefs

Column 3 of A251149.

Formula

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

Empirical g.f.: x*(53 - 72*x - 118*x^2 + 83*x^3 + 74*x^4) / ((1 - x)*(1 + x)*(1 - 2*x)*(1 - x - x^2)). - Colin Barker, Nov 26 2018