A158161 Number of nondecreasing integer sequences of length 27 with sum zero and sum of absolute values 2n.

1, 4, 9, 25, 49, 121, 225, 484, 900, 1764, 3136, 5929, 10201, 18224, 30968, 53323, 88070, 147791, 238887, 390019, 619851, 987327, 1539460, 2407824, 3690457, 5659994, 8550843, 12897622, 19194188, 28531103, 41887361, 61379231, 89025613

Offset

1,2

Links

R. H. Hardin, Table of n, a(n) for n=1..259

Formula

a(n) = A000041(n)^2 for n <= 13.

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

Crossrefs

Sequence in context: A158158 A158159 A158160 * A158162 A158163 A158164

Adjacent sequences: A158158 A158159 A158160 * A158162 A158163 A158164

Keyword

nonn

Author

R. H. Hardin, Mar 13 2009

Status

approved