The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 Please make a donation to keep the OEIS running. We are now in our 56th year. In the past year we added 10000 new sequences and reached almost 9000 citations (which often say "discovered thanks to the OEIS"). Other ways to donate

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A052851 E.g.f.: 1/2 - 1/2*(1+4*log(1-x))^(1/2). 2
 0, 1, 3, 20, 220, 3424, 69008, 1706256, 49956240, 1689497376, 64799254752, 2778906776832, 131756614920192, 6843405231815424, 386414606189283072, 23567401521343170048, 1543994621969805135360, 108137637714495023354880, 8062825821198926369725440 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,3 COMMENTS Previous name was: A simple grammar. LINKS INRIA Algorithms Project, Encyclopedia of Combinatorial Structures 819 FORMULA E.g.f.: 1/2-1/2*(1-4*log(-1/(-1+x)))^(1/2). a(n) = Sum_{k=1..n} stirling1(n,k)*k!*C(2*k-2,k-1)/k*(-1)^(n+k). - Vladimir Kruchinin, May 12 2012 a(n) ~ n^(n-1)/(sqrt(2)*exp(3*n/4)*(exp(1/4)-1)^(n-1/2)). - Vaclav Kotesovec, Sep 30 2013 MAPLE spec := [S, {B=Cycle(Z), S=Prod(B, C), C=Sequence(S)}, labeled]: seq(combstruct[count](spec, size=n), n=0..20); MATHEMATICA CoefficientList[Series[1/2-1/2*(1+4*Log[1-x])^(1/2), {x, 0, 20}], x]* Range[0, 20]! (* Vaclav Kotesovec, Sep 30 2013 *) PROG (Maxima) a(n):=sum(stirling1(n, k)*k!*binomial(2*k-2, k-1)/k*(-1)^(n+k), k, 1, n); \\ Vladimir Kruchinin, May 12 2012 CROSSREFS Sequence in context: A113333 A206405 A307363 * A262233 A058477 A119758 Adjacent sequences:  A052848 A052849 A052850 * A052852 A052853 A052854 KEYWORD easy,nonn AUTHOR encyclopedia(AT)pommard.inria.fr, Jan 25 2000 EXTENSIONS New name using e.g.f., Vaclav Kotesovec, Sep 30 2013 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.

Last modified November 25 13:47 EST 2020. Contains 338623 sequences. (Running on oeis4.)