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A189944 1/4 the number of arrangements of n+1 nonzero numbers x(i) in -2..2 with the sum of sign(x(i))*(|x(i)| mod x(i+1)) equal to zero 1
3, 8, 22, 72, 280, 1152, 4632, 17888, 67232, 251136, 947136, 3625216, 14033664, 54599680, 212521344, 826308096, 3211280896, 12490338304, 48666153984, 189986959360, 742894424064, 2908269379584, 11394480500736, 44672464896000 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Column 2 of A189951

LINKS

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

FORMULA

Empirical: (n+1)*a(n) = 4*(2*n+1)*a(n-1) - 24*n*a(n-2) + 16*(2*n-1)*a(n-3). - Vaclav Kotesovec, Oct 19 2012

EXAMPLE

Some solutions with n=3

..2....2....2....1...-2...-2....1....2....2....1....2...-2...-2...-2...-1...-2

..2....2....2....2....2...-2...-2....2...-2....1....2....2....2...-2....2...-2

..2...-2...-2...-1...-1....1...-1...-1....2...-1...-2....2...-1....2....1...-1

..2...-1...-2....2....1....1....2....1...-2...-1....2...-2...-1....1....2...-1

CROSSREFS

Sequence in context: A171841 A233449 A148770 * A148771 A148772 A148773

Adjacent sequences:  A189941 A189942 A189943 * A189945 A189946 A189947

KEYWORD

nonn

AUTHOR

R. H. Hardin May 02 2011

STATUS

approved

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Last modified September 28 16:11 EDT 2021. Contains 347716 sequences. (Running on oeis4.)