A206500 Number of nX3 0..7 arrays with no element equal to another within a city block distance of two, and new values 0..7 introduced in row major order.

1, 4, 65, 3130, 178998, 10502458, 618242826, 36410671102, 2144479610070, 126304554589462, 7439032094765766, 438141046109721622, 25805450786659366998, 1519878816318690262678, 89517196729004371783830

Offset: 1

Author

R. H. Hardin Feb 08 2012

Keywords

• nonn

Comments

Column 3 of A206503

Examples

			Some solutions for n=4
..0..1..2....0..1..2....0..1..2....0..1..2....0..1..2....0..1..2....0..1..2
..2..3..0....2..3..0....2..3..0....3..4..0....2..3..4....2..3..4....2..3..4
..1..4..5....4..5..1....1..4..5....2..5..1....1..0..5....1..5..6....4..5..1
..5..0..1....1..0..4....5..2..1....0..3..6....3..4..2....3..4..7....6..2..3
		

Links

• R. H. Hardin, Table of n, a(n) for n = 1..62

Formula

Empirical: a(n) = 55*a(n-1) +370*a(n-2) -8556*a(n-3) +15608*a(n-4) +70028*a(n-5) -175808*a(n-6) +98304*a(n-7) for n>9