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A203840 Number of nX2 0..3 arrays with every nonzero element less than or equal to at least two horizontal and vertical neighbors 1
1, 4, 16, 50, 184, 810, 3502, 14751, 63204, 274824, 1195748, 5201911, 22685592, 99123373, 433452835, 1896510229, 8302931200, 36367291798, 159341158550, 698313973844, 3060976848490, 13419502926856, 58838771883237 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Column 2 of A203846

LINKS

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

FORMULA

Empirical: a(n) = 10*a(n-1) -39*a(n-2) +104*a(n-3) -251*a(n-4) +391*a(n-5) -483*a(n-6) +687*a(n-7) -378*a(n-8) +503*a(n-9) -247*a(n-10) -66*a(n-11) -292*a(n-12) -300*a(n-13) -217*a(n-14) -153*a(n-15) -70*a(n-16) -27*a(n-17) -8*a(n-18) -a(n-19)

EXAMPLE

Some solutions for n=4

..3..3....1..1....2..2....3..3....3..3....1..1....1..1....2..2....0..0....0..0

..3..3....2..2....2..2....3..3....3..3....1..1....3..3....3..3....2..2....0..0

..1..1....2..2....0..0....1..1....1..1....2..2....3..3....3..3....2..2....0..0

..0..0....0..0....0..0....0..0....0..0....2..2....0..0....3..3....0..0....0..0

CROSSREFS

Sequence in context: A298173 A323932 A121184 * A089093 A316321 A058234

Adjacent sequences:  A203837 A203838 A203839 * A203841 A203842 A203843

KEYWORD

nonn

AUTHOR

R. H. Hardin Jan 06 2012

STATUS

approved

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Last modified June 16 10:16 EDT 2021. Contains 345056 sequences. (Running on oeis4.)