A203340 Number of nX2 0..4 arrays with every nonzero element less than or equal to at least two horizontal and vertical neighbors

1, 5, 25, 95, 425, 2329, 12487, 64444, 337977, 1804892, 9639699, 51382419, 274455029, 1469096024, 7868330298, 42153003025, 225933068001, 1211463181206, 6497484955682, 34854150590549, 186995102014521, 1003366634580196

Offset

1,2

Comments

Column 2 of A203346

Links

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

Formula

Empirical: a(n) = 15*a(n-1) -95*a(n-2) +395*a(n-3) -1350*a(n-4) +3559*a(n-5) -7390*a(n-6) +14135*a(n-7) -21343*a(n-8) +28527*a(n-9) -37915*a(n-10) +30518*a(n-11) -42342*a(n-12) +18988*a(n-13) -23243*a(n-14) +15396*a(n-15) +7860*a(n-16) +22676*a(n-17) +24262*a(n-18) +22720*a(n-19) +19127*a(n-20) +12868*a(n-21) +7964*a(n-22) +4145*a(n-23) +1861*a(n-24) +726*a(n-25) +227*a(n-26) +58*a(n-27) +11*a(n-28) +a(n-29)

Example

Some solutions for n=5
..4..4....1..1....1..1....2..2....4..4....2..2....3..3....1..1....2..2....0..0
..4..4....3..3....1..1....2..2....4..4....2..2....4..4....2..2....2..2....4..4
..3..4....3..3....4..4....0..2....2..1....1..2....4..4....2..2....2..0....4..4
..4..4....0..0....4..4....3..3....2..2....4..4....3..3....0..0....2..2....4..4
..4..4....0..0....0..0....3..3....2..2....4..4....2..2....0..0....2..2....2..2

Crossrefs

Sequence in context: A203184 A073374 A126878 * A055343 A223945 A197085

Adjacent sequences: A203337 A203338 A203339 * A203341 A203342 A203343

Keyword

nonn

Author

R. H. Hardin Dec 31 2011

Status

approved