The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 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

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

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