OFFSET
4,1
LINKS
Peter Maceli, Class Nine: Random Graphs
FORMULA
a(n) = binomial(n,4)*(4!/8)*2^binomial(n,2). The number of length k cycles in all simple labeled graphs on n nodes is binomial(n,k)*(k!/(2*k))*2^binomial(n,2).
MATHEMATICA
Table[FactorialPower[n, 4]/(8) 2^(Binomial[n, 2] - 4), {n, 0, 15}]
PROG
(Magma) [n*(n-1)*(n-2)*(n-3)/8*2^(Binomial(n, 2)-4): n in [4..20]]; // _Vincenzo Lubrandi_, Nov 27 2016
CROSSREFS
KEYWORD
nonn
AUTHOR
Geoffrey Critzer, Nov 26 2016
STATUS
approved