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A202117 Number of -1..1 arrays of n elements with first, second and third differences also in -1..1 1
3, 7, 13, 19, 27, 35, 47, 65, 91, 129, 185, 267, 387, 563, 821, 1199, 1753, 2565, 3755, 5499, 8055, 11801, 17291, 25337, 37129, 54411, 79739, 116859, 171261, 250991, 367841, 539093, 790075, 1157907, 1696991, 2487057, 3644955, 5341937, 7828985 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Column 1 of A202124

LINKS

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

FORMULA

Empirical: a(n) = 2*a(n-1) -a(n-2) +a(n-3) -a(n-4) for n>8

EXAMPLE

Some solutions for n=7

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

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

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

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

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

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

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

CROSSREFS

Sequence in context: A144917 A102828 A117679 * A100458 A193765 A000960

Adjacent sequences:  A202114 A202115 A202116 * A202118 A202119 A202120

KEYWORD

nonn

AUTHOR

R. H. Hardin Dec 11 2011

STATUS

approved

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Last modified October 21 01:22 EDT 2014. Contains 248371 sequences.