A220565 Number of ways to reciprocally link elements of an 4Xn array either to themselves or to exactly one horizontal or antidiagonal neighbor

1, 34, 292, 3966, 45966, 561636, 6743873, 81437539, 981628768, 11839220919, 142763980945, 1721628751022, 20761198193082, 250361650578082, 3019134246246588, 36408038586112352, 439048064386701057

Offset

1,2

Comments

Row 4 of A220562

Links

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

Formula

Empirical: a(n) = 4*a(n-1) +84*a(n-2) +194*a(n-3) -338*a(n-4) -1077*a(n-5) +616*a(n-6) +1932*a(n-7) -788*a(n-8) -1136*a(n-9) +325*a(n-10) +284*a(n-11) -48*a(n-12) -30*a(n-13) +2*a(n-14) +a(n-15)

Example

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

Crossrefs

Sequence in context: A209891 A027006 A156531 * A230803 A209808 A160146

Adjacent sequences: A220562 A220563 A220564 * A220566 A220567 A220568

Keyword

nonn

Author

R. H. Hardin Dec 16 2012

Status

approved