A201999 - OEIS

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A201999

Number of -1..1 circular arrays x(0..n+1) of n+2 elements with zero sums of x(i) and x(i)*x((i+1) mod (n+2))

1, 9, 11, 43, 85, 329, 577, 1921, 4115, 14331, 32631, 106527, 262481, 833225, 2118711, 6523351, 17225857, 52322449, 141538657, 424472841, 1171251495, 3484084667, 9746606361, 28817241129, 81509487175, 240107776015, 684814280371

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

OFFSET

1,2

COMMENTS

Column 1 of A202006

LINKS

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

EXAMPLE

Some solutions for n=10

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

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

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

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

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

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

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

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

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

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

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

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

CROSSREFS

Sequence in context: A145790 A345109 A143465 * A195309 A242507 A116152

Adjacent sequences: A201996 A201997 A201998 * A202000 A202001 A202002

KEYWORD

nonn

AUTHOR

R. H. Hardin Dec 07 2011

STATUS

approved