A158156 Number of nondecreasing integer sequences of length 22 with sum zero and sum of absolute values 2n.

1, 4, 9, 25, 49, 121, 225, 484, 900, 1764, 3136, 5926, 10183, 18151, 30727, 52631, 86290, 143571, 229623, 370718, 581639, 914103, 1404106, 2163019, 3260010, 4915632, 7292347, 10798752, 15759648, 22972651, 33038402, 47425708, 67328389

Offset

1,2

Links

R. H. Hardin, Table of n, a(n) for n=1..285

Formula

a(n) = A000041(n)^2 for n<=11.

a(n) = A000041(n)^2 - cumulative A000712(2*n-1-length), 0 <= 2*n-1-length <= floor(n/2) [empirical].

Crossrefs

Sequence in context: A158153 A158154 A158155 * A158157 A158158 A158159

Adjacent sequences: A158153 A158154 A158155 * A158157 A158158 A158159

Keyword

nonn

Author

R. H. Hardin, Mar 13 2009

Status

approved