login
This site is supported by donations to The OEIS Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A007081 Number of labeled Eulerian oriented graphs with n nodes.
(Formerly M3009)
1
1, 1, 3, 15, 219, 7839, 777069, 208836207, 156458382975, 328208016021561, 1946879656265710431, 32834193098697741359313, 1582809785794578499063205301, 218989607557709869788340418432175, 87269441106898007902526099850864517077 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

REFERENCES

N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

LINKS

Table of n, a(n) for n=1..15.

B. D. McKay, Applications of a technique for labeled enumeration, Congress. Numerantium, 40 (1983), 207-221.

B. D. McKay, The asymptotic numbers of regular tournaments, Eulerian digraphs and Eulerian oriented graphs, Combinatorica 10 (1990), 367-377.

FORMULA

a(n) = coefficient of [x_1*x_2*...*x_n]^(n-1) in Product_{1<=i<j<=n} (x_i^2 + x_j^2 + x_i*x_j). - Sean A. Irvine, Oct 08 2017

CROSSREFS

Sequence in context: A264705 A117820 A126453 * A126455 A136466 A296856

Adjacent sequences:  A007078 A007079 A007080 * A007082 A007083 A007084

KEYWORD

nonn,nice

AUTHOR

N. J. A. Sloane, Mira Bernstein

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified February 16 21:22 EST 2019. Contains 320199 sequences. (Running on oeis4.)