

A197057


Number of n X 4 0..4 arrays with each element equal to the number its horizontal and vertical neighbors equal to 2.


1



1, 4, 10, 18, 28, 47, 93, 189, 357, 640, 1156, 2162, 4102, 7697, 14243, 26307, 48917, 91394, 170572, 317326, 589634, 1096821, 2042877, 3805343, 7083795, 13181280, 24530278, 45664276, 85014554, 158256855, 294565501, 548276423, 1020572419
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OFFSET

1,2


COMMENTS

Every 0 is next to 0 2's, every 1 is next to 1 2's, every 2 is next to 2 2's, every 3 is next to 3 2's, every 4 is next to 4 2's.
Column 4 of A197061.


LINKS

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


FORMULA

Empirical: a(n) = a(n1) +a(n3) +2*a(n4) +3*a(n5) +2*a(n6) a(n7) 3*a(n8) 2*a(n9).
Empirical g.f.: x*(1 + x)*(1 + x + x^2)*(1 + x + 2*x^2  x^4  2*x^5) / (1  x  x^3  2*x^4  3*x^5  2*x^6 + x^7 + 3*x^8 + 2*x^9).  Colin Barker, May 11 2018


EXAMPLE

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


CROSSREFS

Cf. A197061.
Sequence in context: A217748 A009877 A009880 * A025712 A283969 A022781
Adjacent sequences: A197054 A197055 A197056 * A197058 A197059 A197060


KEYWORD

nonn


AUTHOR

R. H. Hardin, Oct 09 2011


STATUS

approved



