

A202069


Number of arrays of n+2 integers in 1..1 with sum zero and the sum of every adjacent pair being odd


2



2, 4, 2, 0, 6, 12, 6, 0, 20, 40, 20, 0, 70, 140, 70, 0, 252, 504, 252, 0, 924, 1848, 924, 0, 3432, 6864, 3432, 0, 12870, 25740, 12870, 0, 48620, 97240, 48620, 0, 184756, 369512, 184756, 0, 705432, 1410864, 705432, 0, 2704156, 5408312, 2704156, 0, 10400600
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OFFSET

1,1


COMMENTS

Column 1 of A202076


LINKS

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


FORMULA

Empirical: a(n) = f(n mod 4) * binomial(2*z,z), where f(1)=1, f(2)=2, f(3)=1, f(0)=0, and z=floor((n+3)/4)


EXAMPLE

Some solutions for n=10
..0....1...1....1....0...1....0....1....1....0....0....0....0...1....0...1
..1....0....0....0....1....0...1....0....0....1...1....1...1....0...1....0
..0...1...1...1....0....1....0....1....1....0....0....0....0....1....0...1
..1....0....0....0...1....0....1....0....0...1...1....1....1....0....1....0
..0...1....1...1....0....1....0...1....1....0....0....0....0....1....0...1
..1....0....0....0....1....0....1....0....0....1....1...1...1....0....1....0
..0...1....1....1....0...1....0....1...1....0....0....0....0...1....0....1
.1....0....0....0....1....0...1....0....0...1....1...1....1....0...1....0
..0....1....1....1....0....1....0...1...1....0....0....0....0...1....0....1
.1....0....0....0...1....0....1....0....0...1....1....1...1....0...1....0
..0....1...1...1....0...1....0...1...1....0....0....0....0....1....0....1
.1....0....0....0...1....0...1....0....0....1...1...1....1....0....1....0


CROSSREFS

Sequence in context: A277659 A258711 A127278 * A094239 A273240 A201316
Adjacent sequences: A202066 A202067 A202068 * A202070 A202071 A202072


KEYWORD

nonn


AUTHOR

R. H. Hardin Dec 10 2011


STATUS

approved



