

A172286


Numbers of circuits of length 2n in K_{n,n} (the complete bipartite graph on 2n vertices).


1



2, 32, 1458, 131072, 19531250, 4353564672, 1356446145698, 562949953421312, 300189270593998242, 200000000000000000000, 162805498773679522226642, 158993694406781688266883072, 183466660386537233316799232018
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OFFSET

1,1


COMMENTS

Circuits are allowed to be self intersecting and are directional with a designated start node. The number of (self avoiding) directed cycles is given by A010790.  Andrew Howroyd, Sep 05 2018


LINKS

Andrew Howroyd, Table of n, a(n) for n = 1..100


FORMULA

a(n) = 2*n^(2*n).


EXAMPLE

For n=2, a(2) = 32, that is : there are 32 circuits of length 4 in the complete bipartite graph K2,2.


PROG

(MATLAB)
nmax = 10;
for k=1:nmax
an = 2*k^(2*k);
fprintf('%3.0f ', an);
end
(PARI) a(n)=2*n^(2*n); \\ Andrew Howroyd, Sep 05 2018


CROSSREFS

Cf. A010790, A118537.
Sequence in context: A281183 A012209 A295418 * A129348 A280211 A087084
Adjacent sequences: A172283 A172284 A172285 * A172287 A172288 A172289


KEYWORD

easy,nonn


AUTHOR

Thibaut Lienart (syncthib(AT)gmail.com), Jan 30 2010


EXTENSIONS

More terms from Max Alekseyev, Jan 18 2012


STATUS

approved



