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A274699
Number of varied unrooted labeled trees on n nodes, i.e., trees with unique vertex degree except for the leaves.
2
1, 1, 3, 4, 65, 126, 637, 21344, 57465, 330850, 2023901, 156312432, 502733101, 3464645380, 21505493115, 194182086016, 28828634104193, 108228186522378, 842870098110349, 5690185704481040, 49492420589959221, 521939648330427580, 151814675979620347079, 642254623640191155552, 5633344428589261601425, 40942919469553204283076, 370068971963735972601207
OFFSET
1,3
FORMULA
a(n) = (n-2)! Sum_{k=1..n-2} C(n,k) k! [u^k][z^{n-2}] Product_{q=1..n-2} (1 + u z^q/q!).
CROSSREFS
Cf. A007106.
Sequence in context: A349587 A278035 A079076 * A060356 A052323 A356292
KEYWORD
nonn
AUTHOR
Marko Riedel, Jul 02 2016
STATUS
approved