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A183936
Number of strings of n numbers x(i) in -1..1 with sums of x(i) and of x(i)*x(i+1) both zero
1
1, 1, 3, 7, 21, 45, 121, 261, 723, 1723, 5087, 13091, 38641, 101993, 297423, 800187, 2324961, 6378601, 18544345, 51670725, 150172263, 422922591, 1228542913, 3488055573, 10134018375, 28962183951, 84203226523, 241924870591
OFFSET
1,3
COMMENTS
Column 1 of A183944
LINKS
EXAMPLE
All solutions for n=4
..1....0....0...-1...-1....1....0
..0....0....1....0....0....0...-1
.-1....0....0....0....1....0....0
..0....0...-1....1....0...-1....1
CROSSREFS
Sequence in context: A119959 A329114 A018712 * A027151 A219589 A092203
KEYWORD
nonn
AUTHOR
R. H. Hardin Jan 08 2011
STATUS
approved