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!)
A218378 Number of simple labeled graphs on n nodes with all odd size components. 1
1, 1, 1, 5, 17, 769, 4609, 1882805, 15138593, 66365067361, 664157177281, 35645315131333445, 427773958289546417, 301274983519644591252769, 4217875813061550908307649, 40527712572140444650575170520245, 648443738687003872454538321727553 (list; graph; refs; listen; history; text; internal format)
OFFSET
0,4
LINKS
FORMULA
E.g.f.: exp( (A(x) - A(-x))/2 ) where A(x) is the e.g.f. for A001187.
MATHEMATICA
nn=21; a=Sum[2^Binomial[n, 2]x^n/n!, {n, 0, nn}]; c=Range[0, nn]! CoefficientList[Series[ Log[a]+1, {x, 0, nn}], x]; cox= Sum[c[[i]]x^(i-1)/(i-1)!, {i, 2, nn, 2}]; Select[Range[0, nn]! CoefficientList[Series[Exp[cox], {x, 0, nn}], x], #>0&]
CROSSREFS
Sequence in context: A256236 A070294 A245568 * A119531 A248921 A172996
KEYWORD
nonn
AUTHOR
Geoffrey Critzer, Oct 27 2012
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 April 20 10:14 EDT 2024. Contains 371813 sequences. (Running on oeis4.)