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A193129
Number of spanning trees of the n-barbell graph.
1
1, 1, 1, 9, 256, 15625, 1679616, 282475249, 68719476736, 22876792454961, 10000000000000000, 5559917313492231481, 3833759992447475122176, 3211838877954855105157369, 3214199700417740936751087616, 3787675244106352329254150390625
OFFSET
0,4
COMMENTS
a(n) = A000272(n)^2 for n>=0.
LINKS
M. F. Hasler, Table of n, a(n) for n = 0..32 (corrected by Georg Fischer, Jan 20 2019)
Eric Weisstein's World of Mathematics, Barbell Graph
Eric Weisstein's World of Mathematics, Spanning Tree
FORMULA
a(0)=1 and a(n)=n^(2n-4) for n>=1 (from the comment and the formula for A000272).
MATHEMATICA
Table[n^(2 n - 4), {n, 3, 20}]
PROG
(PARI) A193129=n^(2*n-4) \\ M. F. Hasler, Apr 14 2015
CROSSREFS
Cf. A000272.
Sequence in context: A212290 A296950 A025133 * A183493 A183424 A160073
KEYWORD
nonn
AUTHOR
Eric W. Weisstein, Jul 16 2011
STATUS
approved