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

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A052522 Number of labeled mobiles with cycles of length at least 3. 0
0, 1, 0, 2, 6, 64, 540, 6908, 93744, 1542616, 28057800, 576840032, 13029824016, 323152349584, 8698499671680, 252998272144928, 7900336700736864, 263731233726459136, 9370598887948893120, 353114271843930110912 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,4

LINKS

Table of n, a(n) for n=0..19.

INRIA Algorithms Project, Encyclopedia of Combinatorial Structures 90

FORMULA

E.g.f.: (exp(RootOf(2*_Z*exp(_Z)^2 - 5*exp(_Z)^2 + 6*exp(_Z) + 2*x*exp(_Z)^2-1)) -1) / exp(RootOf(2*_Z*exp(_Z)^2 - 5*exp(_Z)^2 + 6*exp(_Z) + 2*x*exp(_Z)^2-1)).

E.g.f. A(x) is the series is reversion of 2*x-1/2*x^2-log(1+x). a(n) = (sum(k=0..n-1, (n+k-1)! * sum(j=0..k, 1/(k-j)! * sum(l=0..j, 1/l! * sum(i=0..l, ((-1)^(i+n+l-1) * 2^(l-2*i) * binomial(l,i) * stirling1(n+j-i-l-1,j-l))/(n+j-i-l-1)!))))), n > 0. - Vladimir Kruchinin, Feb 18 2012

MAPLE

spec := [S, {S=Union(B, Z), B=Cycle(S, 3 <= card)}, labeled]: seq(combstruct[count](spec, size=n), n=0..20);

PROG

(Maxima) a(n):=(sum((n+k-1)! * sum(1/(k-j)! * sum(1/l! * sum(((-1)^(i+n+l-1) * 2^(l-2*i) * binomial(l, i) * stirling1(n+j-i-l-1, j-l)) / (n+j-i-l-1)!, i, 0, l), l, 0, j), j, 0, k), k, 0, n-1)); /* Vladimir Kruchinin, Feb 18 2012 */

CROSSREFS

Sequence in context: A082640 A139695 A241590 * A193609 A061999 A066756

Adjacent sequences:  A052519 A052520 A052521 * A052523 A052524 A052525

KEYWORD

easy,nonn

AUTHOR

encyclopedia(AT)pommard.inria.fr, Jan 25 2000

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 April 22 06:14 EDT 2019. Contains 322329 sequences. (Running on oeis4.)