A281054 Number of nX6 0..1 arrays with no element equal to more than one of its horizontal and antidiagonal neighbors, with the exception of exactly two elements, and with new values introduced in order 0 sequentially upwards.

6, 251, 1403, 5400, 16875, 46610, 119205, 288527, 671451, 1515524, 3339671, 7217269, 15347530, 32196671, 66765699, 137073842, 278977066, 563443975, 1130260537, 2253558987, 4468793135, 8818038639, 17322550753, 33890757331

Offset: 1

Author

R. H. Hardin, Jan 13 2017

Keywords

• nonn

Comments

Column 6 of A281056.

Examples

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

Links

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

Crossrefs

Cf. A281056.

Formula

Empirical: a(n) = 3*a(n-1) +3*a(n-2) -11*a(n-3) -9*a(n-4) +15*a(n-5) +20*a(n-6) +3*a(n-7) -18*a(n-8) -27*a(n-9) -9*a(n-10) +15*a(n-11) +20*a(n-12) +12*a(n-13) -7*a(n-15) -6*a(n-16) -3*a(n-17) -a(n-18) for n>21