A220596 Number of ways to reciprocally link elements of an n X n array either to themselves or to exactly two horizontal, vertical and antidiagonal neighbors, without 3-loops.
1, 2, 65, 9047, 7558495, 41011388731, 1417058414112748, 305516864725171735943, 412489181606705015322075070
Offset: 1
Keywords
Examples
Some solutions for n=3 0=self 2=n 3=ne 4=w 6=e 7=sw 8=s (reciprocal directions total 10) .00.00.00...00.78.78...68.46.47...68.46.48...00.67.48...00.78.00...00.67.47 .00.67.47...38.23.28...28.36.47...28.68.24...38.67.24...38.28.00...38.37.00 .36.34.00...26.46.24...26.34.00...26.24.00...23.00.00...26.24.00...23.00.00
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