A158165 Number of nondecreasing integer sequences of length 31 with sum zero and sum of absolute values 2n.

1, 4, 9, 25, 49, 121, 225, 484, 900, 1764, 3136, 5929, 10201, 18225, 30976, 53360, 88201, 148187, 239961, 392695, 626049, 1000876, 1567506, 2463530, 3796803, 5857417, 8907047, 13527344, 20282712, 30383074, 44979992, 66476896, 97298300

Offset

1,2

Links

R. H. Hardin, Table of n, a(n) for n=1..235

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: A158162 A158163 A158164 * A158166 A158167 A158168

Adjacent sequences: A158162 A158163 A158164 * A158166 A158167 A158168

Keyword

nonn

Author

R. H. Hardin, Mar 13 2009

Status

approved