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A199825 Number of -1..1 arrays x(0..n+1) of n+2 elements with zero sum and no two neighbors summing to zero 1
2, 4, 4, 10, 22, 34, 66, 138, 250, 472, 944, 1806, 3450, 6772, 13172, 25478, 49794, 97348, 189772, 371246, 727506, 1424586, 2793034, 5483342, 10766950, 21154424, 41599648, 81840866, 161080918, 317230034, 625030514, 1231964394, 2429323642 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Column 1 of A199832

LINKS

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

EXAMPLE

All solutions for n=3

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

.-1....1...-1....1

..0....0....0....0

..1...-1....1...-1

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

CROSSREFS

Sequence in context: A193852 A327544 A202076 * A121049 A056415 A242993

Adjacent sequences:  A199822 A199823 A199824 * A199826 A199827 A199828

KEYWORD

nonn

AUTHOR

R. H. Hardin Nov 11 2011

STATUS

approved

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Last modified April 16 18:53 EDT 2021. Contains 343050 sequences. (Running on oeis4.)