A220549 Number of ways to reciprocally link elements of an nX4 array either to themselves or to exactly one horizontal, vertical or antidiagonal neighbor

5, 108, 1814, 32173, 565061, 9943416, 174911750, 3077034244, 54130248568, 952245176313, 16751640356635, 294690365449276, 5184113807856060, 91197538858856819, 1604322628219475789, 28222813114190945744

Offset

1,1

Comments

Column 4 of A220553

Links

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

Formula

Empirical: a(n) = 11*a(n-1) +111*a(n-2) +127*a(n-3) -649*a(n-4) -981*a(n-5) +1615*a(n-6) +2067*a(n-7) -2349*a(n-8) -1177*a(n-9) +1383*a(n-10) +199*a(n-11) -337*a(n-12) +3*a(n-13) +31*a(n-14) -a(n-15) -a(n-16)

Example

Some solutions for n=3 0=self 2=n 3=ne 4=w 6=e 7=sw 8=s (reciprocal directions total 10)
..6..4..7..8....0..0..6..4....6..4..7..7....8..8..0..7....6..4..7..7
..0..3..0..2....0..7..0..8....0..3..3..0....2..2..3..0....0..3..3..0
..6..4..6..4....3..0..0..2....6..4..0..0....0..0..0..0....6..4..6..4

Crossrefs

Sequence in context: A113056 A336436 A318986 * A210904 A306990 A048564

Adjacent sequences: A220546 A220547 A220548 * A220550 A220551 A220552

Keyword

nonn

Author

R. H. Hardin Dec 15 2012

Status

approved