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

 

Logo

Invitation: celebrating 50 years of OEIS, 250000 sequences, and Sloane's 75th, there will be a conference at DIMACS, Rutgers, Oct 9-10 2014.

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A009257 E.g.f. exp(tanh(log(1+x))). 0

%I

%S 1,1,0,-2,4,6,-74,190,1128,-14336,51616,404856,-7330520,41023048,

%T 250083744,-7532037344,65189204416,185746926720,-13324842809792,

%U 175157684686144,-215786634724224,-35458746254274944,711274631768613760

%N E.g.f. exp(tanh(log(1+x))).

%F a(n)=sum(m=1..n, sum(r=0..n-m, stirling1(n,r+m)*sum(k=0..r, binomial(k+m-1,m-1)*(k+m)!*(-1)^(k)*2^(r-k)*stirling2(r+m,k+m)))/m!), n>0, a(0)=1. [From Vladimir Kruchinin, Jun 06 2011]

%t Exp[ Tanh[ Log[ 1+x ] ] ]

%o (Maxima)

%o a(n):=sum(sum(stirling1(n,r+m)*sum(binomial(k+m-1,m-1)*(k+m)!*(-1)^(k)*2^(r-k)*stirling2(r+m,k+m),k,0,r),r,0,n-m)/m!,m,1,n); [From Vladimir Kruchinin, Jun 06 2011]

%K sign,easy

%O 0,4

%A _R. H. Hardin_

%E Extended with signs Mar 15 1997 by _Olivier GĂ©rard_.

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

Content is available under The OEIS End-User License Agreement .

Last modified September 2 02:58 EDT 2014. Contains 246321 sequences.