A331113 Number of signed trees with n positive edges and n negative edges.

1, 1, 9, 96, 1439, 24758, 476056, 9841611, 214997756, 4900190330, 115530636036, 2800145556058, 69446136484047, 1756114394736162, 45152546920446518, 1177790435393100588, 31111743336031473800, 831007304851753985293, 22416683345590695488558, 610057933331757664054671

Offset

0,3

Comments

The total number of nodes is 2n + 1. Trees are unrooted.

Links

Andrew Howroyd, Table of n, a(n) for n = 0..100

Formula

a(n) = A302939(2*n + 1, n).

Crossrefs

Cf. A302939, A331114.

Sequence in context: A070896 A081131 A338105 * A158489 A069636 A069621

Adjacent sequences: A331110 A331111 A331112 * A331114 A331115 A331116

Keyword

nonn

Author

Andrew Howroyd, Jan 09 2020

Status

approved