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 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 0

%I

%S 1,2,30,2586,1485872,5717794568,141539684300104,23071475903430624024,

%T 24446209288705921026670236

%N 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

%C Diagonal of A220725

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

%e .00.67.47...00.00.00...00.79.00...00.69.47...69.46.47...00.79.00...00.67.47

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

%e .00.16.14...00.16.14...36.34.00...36.34.00...00.00.00...36.14.00...00.00.00

%K nonn

%O 1,2

%A _R. H. Hardin_ Dec 18 2012

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Last modified January 23 13:46 EST 2020. Contains 331171 sequences. (Running on oeis4.)