A201866 - OEIS

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A201866

Number of zero-sum -1..1 arrays of n elements with first and second differences also in -1..1

1, 1, 3, 3, 5, 11, 21, 39, 73, 129, 229, 407, 733, 1335, 2461, 4549, 8427, 15585, 28811, 53235, 98479, 182403, 338461, 628873, 1169875, 2177875, 4056997, 7561019, 14098931, 26303445, 49100159, 91702815, 171359391, 320357055, 599167829

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,3

COMMENTS

Column 1 of A201873

LINKS

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

EXAMPLE

Some solutions for n=10

..1....1....1...-1...-1....0...-1....1....0...-1...-1....1....0....0...-1...-1

..1....1....1....0....0....0....0....1...-1...-1...-1....1....1....0....0...-1

..0....0....1....0....0....0....1....0...-1...-1...-1....1....1...-1....0....0

.-1....0....0...-1....0....0....1....0....0....0....0....1....0...-1....0....0

.-1....0....0...-1....1....0....1....0....0....0....0....0...-1...-1....0....1

.-1....0...-1....0....1...-1....0....0....0....0....1....0...-1....0....1....1

.-1....0...-1....1....0...-1....0...-1....0....1....1...-1...-1....0....1....1

..0...-1...-1....1....0....0...-1...-1....0....1....0...-1....0....1....0....0

..1...-1....0....1....0....1...-1....0....1....1....0...-1....0....1....0....0

..1....0....0....0...-1....1....0....0....1....0....1...-1....1....1...-1...-1

CROSSREFS

Sequence in context: A073749 A299590 A250396 * A191632 A146918 A093306

Adjacent sequences: A201863 A201864 A201865 * A201867 A201868 A201869

KEYWORD

nonn

AUTHOR

R. H. Hardin Dec 06 2011

STATUS

approved