A220568 Number of ways to reciprocally link elements of an 7Xn array either to themselves or to exactly one horizontal or antidiagonal neighbor

1, 610, 27716, 3128843, 252139015, 22926570957, 1996515036228, 176531479976571, 15526120567015962, 1368042952494285120, 120466174602717968172, 10610162775514570773634, 934433508779628038701082

Offset

1,2

Comments

Row 7 of A220562

Links

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

Example

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

Crossrefs

Sequence in context: A120719 A045730 A072317 * A189455 A224171 A223862

Adjacent sequences: A220565 A220566 A220567 * A220569 A220570 A220571

Keyword

nonn

Author

R. H. Hardin Dec 16 2012

Status

approved