A220737 Number of ways to reciprocally link elements of an nX7 array either to themselves or to exactly two horizontal, diagonal and antidiagonal neighbors, without consecutive collinear links

1, 221, 10653, 824965, 60293428, 4335687696, 319803318494, 23223803317197, 1694411878011549, 123510214821475772, 9003987952938394208, 656405668520539476077, 47851358998828374751289, 3488414479767358266768461

Offset

1,2

Comments

Column 7 of A220738

Links

R. H. Hardin, Table of n, a(n) for n = 1..115

Example

Some solutions for n=3 0=self 1=nw 3=ne 4=w 6=e 7=sw 9=se (reciprocal directions total 10)
.00.67.49.00.00.79.00...00.79.79.79.00.00.00...00.67.47.00.00.00.00
.39.00.79.17.39.67.14...39.39.13.16.14.69.47...39.39.79.00.00.00.00
.00.13.36.14.36.14.00...00.16.14.00.00.36.14...00.13.16.14.00.00.00

Crossrefs

Sequence in context: A020247 A177422 A177420 * A220723 A011816 A048902

Adjacent sequences: A220734 A220735 A220736 * A220738 A220739 A220740

Keyword

nonn

Author

R. H. Hardin Dec 18 2012

Status

approved