login
The OEIS is supported by the many generous donors to the OEIS Foundation.

 

Logo
Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A054956 Number of labeled Eulerian digraphs with n nodes and an odd number of edges. 4
0, 0, 2, 64, 3808, 687616, 438948304, 1023160166400, 8829110850999296, 284886609918480818176, 34640035331694391925165824, 15970703846423879100651622752256, 28060860469435555251136195646902620160, 188681219498365676664628141013181314824798208 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

LINKS

Table of n, a(n) for n=1..14.

V. A. Liskovets, Some easily derivable sequences, J. Integer Sequences, 3 (2000), #00.2.2.

FORMULA

a(n) = (A007080(n) - n!)/2. - Andrew Howroyd, Sep 10 2018

MATHEMATICA

A007080 = Cases[Import["https://oeis.org/A007080/b007080.txt", "Table"], {_, _}][[All, 2]];

a[n_] := (A007080[[n]] - n!)/2;

Array[a, 14] (* Jean-François Alcover, Aug 27 2019 *)

CROSSREFS

Cf. A007080, A054955.

Sequence in context: A010047 A187548 A300640 * A210930 A263185 A155957

Adjacent sequences: A054953 A054954 A054955 * A054957 A054958 A054959

KEYWORD

nonn,easy

AUTHOR

N. J. A. Sloane, May 24 2000

EXTENSIONS

More terms from Vladeta Jovovic, Mar 05 2001

a(12)-a(14) from Andrew Howroyd, Sep 10 2018

STATUS

approved

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

License Agreements, Terms of Use, Privacy Policy. .

Last modified January 26 19:00 EST 2023. Contains 359833 sequences. (Running on oeis4.)