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A196537 Number of nX1 0..4 arrays with each element equal to the number its horizontal and vertical neighbors less than or equal to itself 3
1, 3, 2, 7, 19, 35, 77, 176, 377, 819, 1801, 3927, 8562, 18711, 40855, 89179, 194729, 425184, 928305, 2026855, 4425441, 9662395, 21096706, 46062279, 100571611, 219586403, 479441557, 1046805072, 2285577449, 4990293595, 10895727817 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Column 1 of A196544

LINKS

R. H. Hardin, Table of n, a(n) for n = 1..200

FORMULA

Empirical: a(n) = a(n-1) +a(n-2) +3*a(n-3) +a(n-4).

Empirical: G.f. x*(x-1)*(x^2+3*x+1) / ( -1+x+x^2+3*x^3+x^4 ). - R. J. Mathar, Jul 25 2012

EXAMPLE

All solutions for n=4

..0....0....1....0....0....1....0

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

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

..0....0....0....1....0....0....1

CROSSREFS

Sequence in context: A049970 A104528 A177115 * A173099 A111928 A248054

Adjacent sequences:  A196534 A196535 A196536 * A196538 A196539 A196540

KEYWORD

nonn

AUTHOR

R. H. Hardin Oct 03 2011

STATUS

approved

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Last modified November 18 10:38 EST 2017. Contains 294887 sequences.