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

Author

R. H. Hardin Dec 17 2012

Keywords

• nonn

Comments

Column 6 of A220621

Examples

			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
		

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) [phone]*a(n-8) [phone]*a(n-9) -425367914*a(n-10) -207014564*a(n-11) [phone]*a(n-12) [phone]*a(n-13) -2364082704*a(n-14) -29030256*a(n-15) [phone]*a(n-16) [phone]*a(n-17) -215936884*a(n-18) -545425394*a(n-19) -380424104*a(n-20) [phone]*a(n-21) [phone]*a(n-22) -120388312*a(n-23) -52194454*a(n-24) [phone]*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)