A268626 Number of nX6 0..2 arrays with some element plus some horizontally or vertically adjacent neighbor totalling two no more than once.

336, 8586, 187224, 3819654, 74914554, 1430057208, 26758514760, 493042858032, 8974328440044, 161737670836314, 2891047134413940, 51321708535136676, 905714517532142694, 15902932976899644264, 277998507169027800234

Offset: 1

Author

R. H. Hardin, Feb 09 2016

Keywords

• nonn

Comments

Column 6 of A268628.

Examples

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

Links

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

Crossrefs

Cf. A268628.

Formula

Empirical: a(n) = 60*a(n-1) -1482*a(n-2) +20016*a(n-3) -167163*a(n-4) +924894*a(n-5) -3537110*a(n-6) +9593166*a(n-7) -18693789*a(n-8) [phone]*a(n-9) -26188161*a(n-10) [phone]*a(n-11) -8262712*a(n-12) +2220864*a(n-13) -266256*a(n-14) for n>15