A220623 Number of ways to reciprocally link elements of an 4Xn array either to themselves or to exactly one horizontal, diagonal and antidiagonal neighbor

1, 71, 765, 17084, 282777, 5280827, 93905509, 1703300073, 30648000256, 553256525421, 9974206108397, 179912817659011, 3244530759637569, 58516690759430228, 1055339507419304093, 19033159346284815815

Offset

1,2

Comments

Row 4 of A220621

Links

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

Formula

Empirical: a(n) = 14*a(n-1) +98*a(n-2) -452*a(n-3) -102*a(n-4) +876*a(n-5) -144*a(n-6) -268*a(n-7) +22*a(n-8) -8*a(n-9) +15*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..6..4....6..4..0....6..4..0....0..6..4....0..7..0....0..0..7....9..9..0
..0..6..4....6..4..0....0..9..0....0..9..0....3..9..0....0..3..0....0..1..1
..0..7..7....0..0..0....9..0..1....0..0..1....0..0..1....9..7..0....6..4..0
..3..3..0....0..6..4....0..1..0....0..0..0....6..4..0....3..1..0....6..4..0

Crossrefs

Sequence in context: A112750 A351896 A089706 * A173806 A253683 A210699

Adjacent sequences: A220620 A220621 A220622 * A220624 A220625 A220626

Keyword

nonn

Author

R. H. Hardin Dec 17 2012

Status

approved