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A220680 Number of ways to reciprocally link elements of an nX7 array either to themselves or to exactly two horizontal, vertical and antidiagonal neighbors, without consecutive collinear links 1

%I #4 Dec 17 2012 16:02:06

%S 1,441,22000,2316754,215926776,21051034046,2045717834201,

%T 198460804181024,19267871745544463,1870273847823355410,

%U 181541549823743511322,17622155633363587138681,1710539337273283386055832

%N Number of ways to reciprocally link elements of an nX7 array either to themselves or to exactly two horizontal, vertical and antidiagonal neighbors, without consecutive collinear links

%C Column 7 of A220681

%H R. H. Hardin, <a href="/A220680/b220680.txt">Table of n, a(n) for n = 1..107</a>

%e Some solutions for n=3 0=self 2=n 3=ne 4=w 6=e 7=sw 8=s (reciprocal directions total 10)

%e .00.00.00.00.78.00.00...00.78.00.67.48.68.47...00.00.00.00.68.48.00

%e .68.48.00.38.27.78.00...38.27.38.00.27.23.78...00.00.68.48.26.24.78

%e .26.24.00.23.36.24.00...23.00.26.34.00.36.24...00.00.26.24.00.36.24

%K nonn

%O 1,2

%A _R. H. Hardin_ Dec 17 2012

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