A158152 Number of nondecreasing integer sequences of length 18 with sum zero and sum of absolute values 2n.

1, 4, 9, 25, 49, 121, 225, 484, 900, 1761, 3118, 5855, 9954, 17513, 29161, 49089, 78882, 128692, 201207, 317716, 486382, 745954, 1116059, 1675856, 2456983, 3606019, 5200369, 7489188, 10616424, 15042972, 21003699, 29292406, 40365840, 55491448

Offset

1,2

Links

R. H. Hardin, Table of n, a(n) for n=1..350

Formula

a(n) = A000041(n)^2 for n <= 9.

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

Crossrefs

Column k=18 of A389686.

Sequence in context: A158149 A158150 A158151 * A158153 A158154 A158155

Adjacent sequences: A158149 A158150 A158151 * A158153 A158154 A158155

Keyword

nonn

Author

R. H. Hardin, Mar 13 2009

Status

approved