A220719 - OEIS

A220719

Number of ways to reciprocally link elements of an n X n array either to themselves or to exactly two horizontal, diagonal or antidiagonal neighbors

1, 2, 30, 2586, 1485872, 5717794568, 141539684300104, 23071475903430624024, 24446209288705921026670236

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,2

COMMENTS

Diagonal of A220725

LINKS

EXAMPLE

Some solutions for n=3 0=self 1=nw 3=ne 4=w 6=e 7=sw 9=se (reciprocal directions total 10)

.00.67.47...00.00.00...00.79.00...00.69.47...69.46.47...00.79.00...00.67.47

.39.39.00...69.49.00...36.47.17...00.37.17...00.13.00...39.67.14...36.34.00

.00.16.14...00.16.14...36.34.00...36.34.00...00.00.00...36.14.00...00.00.00

CROSSREFS

KEYWORD

nonn

AUTHOR

STATUS

approved