A158164 Number of nondecreasing integer sequences of length 30 with sum zero and sum of absolute values 2n.

1, 4, 9, 25, 49, 121, 225, 484, 900, 1764, 3136, 5929, 10201, 18225, 30976, 53358, 88191, 148151, 239851, 392395, 625299, 999124, 1563656, 2455480, 3780743, 5826519, 8849597, 13423122, 20098272, 30062630, 44434404, 65561648, 95788280

Offset

1,2

Links

R. H. Hardin, Table of n, a(n) for n=1..238

Formula

a(n) = A000041(n)^2 for n <= 15.

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

Crossrefs

Sequence in context: A158161 A158162 A158163 * A158165 A158166 A158167

Adjacent sequences: A158161 A158162 A158163 * A158165 A158166 A158167

Keyword

nonn

Author

R. H. Hardin, Mar 13 2009

Status

approved