A189943 1/4 the number of arrangements of n+1 nonzero numbers x(i) in -n..n with the sum of sign(x(i))*(|x(i)| mod x(i+1)) equal to zero

1, 8, 63, 1246, 31284, 839968, 26586582, 1012894742, 43952718714, 2154085255777, 116337778510833, 6974910796570573, 453756196177752909, 32037319291934188145, 2433852671789915900894, 198648198467160364716000

Offset

1,2

Comments

Diagonal of A189951

Links

R. H. Hardin, Table of n, a(n) for n = 1..18

Example

Some solutions with n=3
.-2...-3...-2...-2....3....3...-2....1...-1....2...-3...-2...-3...-1....1....3
.-1....1...-1....1...-2...-2....2...-2....2....1....3....2....1....1....1....2
..1...-3....3...-1...-1....3....2...-1...-3...-3...-3...-2....1....1...-1...-1
.-1....2...-2....1...-3....2...-2...-2...-2...-2....1...-2...-1...-1...-1....2

Crossrefs

Sequence in context: A084096 A361238 A353993 * A358324 A137664 A317028

Adjacent sequences: A189940 A189941 A189942 * A189944 A189945 A189946

Keyword

nonn

Author

R. H. Hardin May 02 2011

Status

approved