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

Author

Andrew Howroyd, Jan 09 2020

Keywords

• nonn

Comments

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

Links

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

Crossrefs

Cf. A302939, A331114.

Formula

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