A220635 Number of ways to reciprocally link elements of an 5Xn array either to themselves or to exactly two horizontal or antidiagonal neighbors

1, 1, 8, 114, 1481, 17527, 201903, 2329448, 26904225, 310837917, 3591561452, 41499180881, 479508472309, 5540546671074, 64018957168901, 739714921940047, 8547125318062702, 98758781455779205, 1141120102778497151

Offset

1,3

Comments

Row 5 of A220632

Links

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

Formula

Empirical: a(n) = 16*a(n-1) -39*a(n-2) -186*a(n-3) +419*a(n-4) +1024*a(n-5) -1049*a(n-6) -2258*a(n-7) +861*a(n-8) +2000*a(n-9) -133*a(n-10) -586*a(n-11) -16*a(n-12) +32*a(n-13) for n>17

Example

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

Crossrefs

Sequence in context: A217772 A062126 A222520 * A113670 A347019 A156468

Adjacent sequences: A220632 A220633 A220634 * A220636 A220637 A220638

Keyword

nonn

Author

R. H. Hardin Dec 17 2012

Status

approved