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

1,1

Comments

Column 4 of A220621

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)

Example

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

Crossrefs

Sequence in context: A232489 A318219 A182963 * A231702 A069948 A316727

Adjacent sequences: A220614 A220615 A220616 * A220618 A220619 A220620

Keyword

nonn

Author

R. H. Hardin Dec 17 2012

Status

approved