A220617 Number of ways to reciprocally link elements of an nX4 array either to themselves or to exactly one horizontal, diagonal and antidiagonal neighbor.

5, 87, 1189, 17084, 243119, 3466455, 49406943, 704243629, 10038098456, 143080761421, 2039439299333, 29069688249415, 414352491974681, 5906082889319188, 84183915242486395, 1199937711608731991

Offset: 1

Author

R. H. Hardin Dec 17 2012

Keywords

• nonn

Comments

Column 4 of A220621

Examples

			Some solutions for n=3 0=self 1=nw 3=ne 4=w 6=e 7=sw 9=se (reciprocal directions total 10)
..0..9..6..4....0..0..6..4....0..6..4..0....9..7..0..0....9..7..0..0
..0..7..1..0....0..0..0..0....0..0..0..7....3..1..6..4....3..1..6..4
..3..0..0..0....0..0..6..4....0..0..3..0....0..0..0..0....0..6..4..0
		

Links

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

Formula

Empirical: a(n) = 16*a(n-1) -18*a(n-2) -114*a(n-3) +230*a(n-4) -66*a(n-5) -78*a(n-6) +48*a(n-7) -4*a(n-8) -4*a(n-9) +a(n-10)