A183921 Number of nondecreasing arrangements of n numbers in -3..3 with sum zero and sum of squares not greater than n*12/3

1, 3, 5, 12, 22, 39, 63, 104, 155, 226, 324, 452, 612, 827, 1087, 1415, 1817, 2306, 2886, 3593, 4417, 5395, 6537, 7868, 9392, 11172, 13180, 15484, 18100, 21058, 24372, 28134, 32298, 36967, 42161, 47920, 54266, 61327, 69043, 77548, 86872, 97071, 108168

Offset

1,2

Comments

Column 3 of A183927

Links

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

Formula

Empirical: a(n)=2*a(n-1)-a(n-2)-a(n-5)+2*a(n-6)-a(n-7)+a(n-8)-a(n-9)-a(n-10)+a(n-11)+a(n-13)-a(n-14)-a(n-16)+2*a(n-18)-a(n-19)+a(n-20)-2*a(n-21)+a(n-23)+a(n-24)-a(n-25)-a(n-28)+2*a(n-29)-a(n-30)-a(n-33)+2*a(n-34)-a(n-35)-a(n-38)+a(n-39)+a(n-40)-2*a(n-42)+a(n-43)-a(n-44)+2*a(n-45)-a(n-47)-a(n-49)+a(n-50)+a(n-52)-a(n-53)-a(n-54)+a(n-55)-a(n-56)+2*a(n-57)-a(n-58)-a(n-61)+2*a(n-62)-a(n-63)

Example

All solutions for n=4
.-1...-2....0...-1...-2...-3...-2...-2...-1...-3...-1...-2
.-1...-1....0...-1....0....1...-1...-2....0....0...-1....0
..1....0....0....0....1....1....1....2....0....1...-1....0
..1....3....0....2....1....1....2....2....1....2....3....2

Crossrefs

Sequence in context: A234005 A263346 A034763 * A177143 A191391 A121482

Adjacent sequences: A183918 A183919 A183920 * A183922 A183923 A183924

Keyword

nonn

Author

R. H. Hardin Jan 08 2011

Status

approved