A220615 Number of ways to reciprocally link elements of an n X n array either to themselves or to exactly one horizontal, diagonal and antidiagonal neighbor

1, 7, 125, 17084, 8608738, 24177895648, 304265433695569, 19162399246164949616, 5720357296116644040788320, 8308397301115322562870135405329, 57991968922890673398646650823295660128

Offset

1,2

Comments

Diagonal of A220621

Links

Table of n, a(n) for n=1..11.

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..7....0..6..4....0..0..0....6..4..0....0..0..0....9..0..0....0..9..0
..9..3..1....0..7..7....0..0..0....0..6..4....0..9..0....0..1..0....0..7..1
..0..1..0....3..3..0....0..0..0....0..0..0....6..4..1....0..6..4....3..0..0

Crossrefs

Sequence in context: A304420 A217910 A316276 * A113162 A180583 A295412

Adjacent sequences: A220612 A220613 A220614 * A220616 A220617 A220618

Keyword

nonn

Author

R. H. Hardin Dec 17 2012

Status

approved