login

Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 61st year, we have over 378,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”).

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