A220711 Number of ways to reciprocally link elements of an 6Xn array either to themselves or to exactly two horizontal and antidiagonal neighbors, without consecutive collinear links

1, 1, 13, 60, 317, 1617, 8338, 42873, 221082, 1139020, 5870960, 30259204, 155962396, 803874071, 4143371101, 21356146495, 110075467413, 567360680620, 2924337273221, 15072870834560, 77689863937436, 400435729023800

Offset

1,3

Comments

Row 6 of A220708

Links

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

Formula

Empirical: a(n) = a(n-1) +33*a(n-2) -a(n-3) -351*a(n-4) -75*a(n-5) +1760*a(n-6) +436*a(n-7) -4708*a(n-8) -997*a(n-9) +6997*a(n-10) +1085*a(n-11) -5748*a(n-12) -564*a(n-13) +2512*a(n-14) +131*a(n-15) -543*a(n-16) -7*a(n-17) +49*a(n-18) -a(n-19) -a(n-20) for n>24

Example

Some solutions for n=3 0=self 3=ne 4=w 6=e 7=sw (reciprocal directions total 10)
.00.67.47...00.00.00...00.00.00...00.00.00...00.67.47...00.00.00...00.00.00
.36.34.00...00.67.47...00.00.00...00.00.00...36.34.00...00.67.47...00.00.00
.00.00.00...36.34.00...00.00.00...00.00.00...00.67.47...36.34.00...00.67.47
.00.67.47...00.67.47...00.00.00...00.00.00...36.34.00...00.00.00...36.34.00
.36.34.00...36.34.00...00.00.00...00.67.47...00.00.00...00.00.00...00.00.00
.00.00.00...00.00.00...00.00.00...36.34.00...00.00.00...00.00.00...00.00.00

Crossrefs

Sequence in context: A126400 A297962 A354670 * A295915 A219925 A228282

Adjacent sequences: A220708 A220709 A220710 * A220712 A220713 A220714

Keyword

nonn

Author

R. H. Hardin Dec 18 2012

Status

approved