This site is supported by donations to The OEIS Foundation.



The submissions stack has been unacceptably high for several months now. Please voluntarily restrict your submissions and please help with the editing. (We don't want to have to impose further limits.)

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


%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 With[{nn=30},CoefficientList[Series[Exp[Tanh[Log[1+x]]],{x,0,nn}],x] Range[0,nn]!] (* _Harvey P. Dale_, Jan 15 2015 *)

%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_.

%E Prior Mathematica program replaced by _Harvey P. Dale_, Jan 15 2015

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 August 29 08:06 EDT 2015. Contains 261188 sequences.