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A068087
a(n) = n^(2*n-2).
6
1, 4, 81, 4096, 390625, 60466176, 13841287201, 4398046511104, 1853020188851841, 1000000000000000000, 672749994932560009201, 552061438912436417593344, 542800770374370512771595361, 629983141281877223603213172736, 852226929923929274082183837890625
OFFSET
1,2
COMMENTS
Number of spanning trees in the bipartite graph K(n,n). In general the number of spanning trees in the bipartite graph K(m,n) is m^(n-1) * n^(m-1).
LINKS
Eric Weisstein's World of Mathematics, Complete Bipartite Graph
Eric Weisstein's World of Mathematics, Spanning Tree
PROG
(PARI) a(n)=n^(2*n-2) \\ Charles R Greathouse IV, Mar 31 2016
CROSSREFS
a(n) = A000169(n)^2.
Sequence in context: A268206 A337155 A268105 * A324088 A357513 A090599
KEYWORD
nonn,easy
AUTHOR
Sharon Sela (sharonsela(AT)hotmail.com), May 06 2002
STATUS
approved