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A331113
Number of signed trees with n positive edges and n negative edges.
3
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
FORMULA
a(n) = A302939(2*n + 1, n).
CROSSREFS
Sequence in context: A070896 A081131 A338105 * A158489 A069636 A069621
KEYWORD
nonn
AUTHOR
Andrew Howroyd, Jan 09 2020
STATUS
approved