A198522 Number of n X 2 0..4 arrays with values 0..4 introduced in row major order and each element equal to no more than two horizontal and vertical neighbors.

2, 15, 193, 3660, 81844, 1948672, 47436498, 1163606279, 28617909415, 704465305625, 17346617064022, 427184684002131, 10520398796919219, 259092051772297458, 6380839372392481249, 157145577058895542027

Offset: 1

Author

R. H. Hardin Oct 26 2011

Keywords

• nonn

Comments

Column 2 of A198528.

Examples

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

Links

• R. H. Hardin, Table of n, a(n) for n = 1..200

Crossrefs

Cf. A198528.

Formula

Empirical: a(n) = 35*a(n-1) -267*a(n-2) +246*a(n-3) +924*a(n-4) +710*a(n-5) -1736*a(n-6) -1860*a(n-7) +72*a(n-8) +1984*a(n-9) +720*a(n-10) -320*a(n-11) -512*a(n-12) for n > 14.