A220591 Number of ways to reciprocally link elements of an nX3 array either to themselves or to exactly two king-move neighbors

1, 33, 423, 6156, 87542, 1250507, 17847210, 254759570, 3636434730, 51906768670, 740920520709, 10575949381405, 150961805783944, 2154838890134463, 30758314061665953, 439046226888854973, 6266975132151978539

Offset

1,2

Comments

Column 3 of A220595

Links

R. H. Hardin, Table of n, a(n) for n = 1..210

Formula

Empirical: a(n) = 11*a(n-1) +46*a(n-2) +14*a(n-3) -46*a(n-4) -63*a(n-5) +35*a(n-6) +20*a(n-7) +a(n-8) -4*a(n-9) -a(n-10)

Example

Some solutions for n=3 0=self 1=nw 2=n 3=ne 4=w 6=e 7=sw 8=s 9=se (reciprocal directions total 10)
.00.67.48...69.47.00...00.68.48...00.79.00...89.78.00...00.00.78...68.46.48
.38.89.28...38.18.00...00.29.28...39.68.14...23.12.00...00.37.27...28.79.28
.26.24.12...26.24.00...00.00.12...00.12.00...00.00.00...36.34.00...23.00.12

Crossrefs

Sequence in context: A324950 A252925 A107965 * A296839 A296988 A367983

Adjacent sequences: A220588 A220589 A220590 * A220592 A220593 A220594

Keyword

nonn

Author

R. H. Hardin Dec 16 2012

Status

approved