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A203340 Number of nX2 0..4 arrays with every nonzero element less than or equal to at least two horizontal and vertical neighbors 1
1, 5, 25, 95, 425, 2329, 12487, 64444, 337977, 1804892, 9639699, 51382419, 274455029, 1469096024, 7868330298, 42153003025, 225933068001, 1211463181206, 6497484955682, 34854150590549, 186995102014521, 1003366634580196 (list; graph; refs; listen; history; text; internal format)
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

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Last modified February 25 08:42 EST 2020. Contains 332221 sequences. (Running on oeis4.)