A208874 Number of 3Xn 0..3 arrays with new values 0..3 introduced in row major order and no element equal to more than one of its immediate leftward or upward or right-upward antidiagonal neighbors.

5, 143, 6520, 307165, 14493405, 683903931, 32271626438, 1522813452263, 71857577327143, 3390770839381669, 160001593732718856, 7550056082308516761, 356267369073405009281, 16811323900505484274607, 793282337427660173475274

Offset: 1

Author

R. H. Hardin Mar 02 2012

Keywords

• nonn

Comments

Row 3 of A208872

Examples

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

Links

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

Formula

Empirical: a(n) = 61*a(n-1) -722*a(n-2) +3476*a(n-3) -7851*a(n-4) +8583*a(n-5) -4266*a(n-6) +720*a(n-7) for n>8