A220619 Number of ways to reciprocally link elements of an nX6 array either to themselves or to exactly one horizontal, diagonal and antidiagonal neighbor

13, 1215, 76955, 5280827, 356768525, 24177895648, 1637496710797, 110916199227139, 7512747980759983, 508867505795261823, 34467532553765146717, 2334617570886588879553, 158132555108084876751600

Offset

1,1

Comments

Column 6 of A220621

Links

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

Formula

Empirical: a(n) = 75*a(n-1) -234*a(n-2) -18880*a(n-3) +81906*a(n-4) +899610*a(n-5) -3495200*a(n-6) -14871391*a(n-7) +57262153*a(n-8) +94978240*a(n-9) -425367914*a(n-10) -207014564*a(n-11) +1449829450*a(n-12) +111910344*a(n-13) -2364082704*a(n-14) -29030256*a(n-15) +1700883948*a(n-16) +349734858*a(n-17) -215936884*a(n-18) -545425394*a(n-19) -380424104*a(n-20) +341201464*a(n-21) +219237544*a(n-22) -120388312*a(n-23) -52194454*a(n-24) +28101292*a(n-25) +7351846*a(n-26) -4063344*a(n-27) -843527*a(n-28) +300917*a(n-29) +79254*a(n-30) -10858*a(n-31) -4326*a(n-32) +168*a(n-33) +112*a(n-34) -a(n-35) -a(n-36)

Example

Some solutions for n=3 0=self 1=nw 3=ne 4=w 6=e 7=sw 9=se (reciprocal directions total 10)
..6..4..0..6..4..0....0..7..9..7..0..0....9..9..9..0..6..4....6..4..9..0..9..0
..0..9..7..9..9..0....3..7..3..1..6..4....0..1..1..1..7..0....9..9..0..1..7..1
..0..3..1..0..1..1....3..0..0..6..4..0....0..6..4..3..6..4....0..1..1..3..0..0

Crossrefs

Sequence in context: A201265 A221390 A226095 * A178560 A091781 A156641

Adjacent sequences: A220616 A220617 A220618 * A220620 A220621 A220622

Keyword

nonn

Author

R. H. Hardin Dec 17 2012

Status

approved