A188271 Number of nondecreasing strings of numbers x(i=1..n) in -3..3 with sum x(i)^3 equal to 0

1, 4, 4, 10, 10, 20, 22, 37, 45, 68, 88, 122, 160, 214, 276, 359, 451, 574, 704, 880, 1066, 1310, 1572, 1899, 2257, 2682, 3158, 3710, 4328, 5038, 5824, 6725, 7707, 8834, 10054, 11444, 12948, 14640, 16476, 18511, 20729, 23166, 25818, 28718, 31860, 35290, 38980

Offset

1,2

Comments

Column 3 of A188277

Links

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

Formula

Empirical: a(n)=a(n-1)+2*a(n-2)-2*a(n-3)-a(n-4)+a(n-5)+a(n-9)-a(n-10)-2*a(n-11)+2*a(n-12)+a(n-13)-a(n-14)+a(n-28)-a(n-29)-2*a(n-30)+2*a(n-31)+a(n-32)-a(n-33)+a(n-35)-a(n-36)-3*a(n-37)+3*a(n-38)+3*a(n-39)-3*a(n-40)-a(n-41)+a(n-42)-a(n-44)+a(n-45)+2*a(n-46)-2*a(n-47)-a(n-48)+a(n-49)-a(n-63)+a(n-64)+2*a(n-65)-2*a(n-66)-a(n-67)+a(n-68)+a(n-72)-a(n-73)-2*a(n-74)+2*a(n-75)+a(n-76)-a(n-77)

Example

Some solutions for n=8 k=3
.-1...-1....0...-3...-3...-2...-2...-3...-2...-1...-3...-3...-3...-2...-1...-3
.-1...-1....0...-3...-3....0...-1...-3...-2....0...-3...-3....0...-2...-1...-3
.-1...-1....0...-2...-2....0...-1...-3....0....0...-3...-3....1...-2....0...-3
..0...-1....0...-2...-1....0...-1...-1....0....0....0...-3....1...-1....0...-2
..0....1....0....2....1....0....1....1....0....0....0....3....1...-1....0....2
..1....1....0....2....2....0....1....3....0....0....3....3....2...-1....0....3
..1....1....0....3....3....0....1....3....2....0....3....3....2....0....1....3
..1....1....0....3....3....2....2....3....2....1....3....3....2....3....1....3

Crossrefs

Sequence in context: A101256 A116569 A058187 * A219939 A219471 A006477

Adjacent sequences: A188268 A188269 A188270 * A188272 A188273 A188274

Keyword

nonn

Author

R. H. Hardin Mar 26 2011

Status

approved