The OEIS is supported by the many generous donors to the OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A159592 G.f.: Sum_{n>=0} a(n)*x^n/2^(n(n-1)/2) = exp( Sum_{n>=1} A(x/2^n)^n*x^n/n ). 1

%I #2 Mar 30 2012 18:37:17

%S 1,1,3,17,177,3491,133261,9917307,1443008813,411772442315,

%T 231163433300285,255964900099068155,560177408302962464013,

%U 2427068640913282843197355,20848444510025384551575108829

%N G.f.: Sum_{n>=0} a(n)*x^n/2^(n(n-1)/2) = exp( Sum_{n>=1} A(x/2^n)^n*x^n/n ).

%e G.f.: A(x) = 1 + x + 3*x^2/2 + 17*x^3/2^3 + 177*x^4/2^6 + 3491*x^5/2^10 +...

%e log(A(x)) = A(x/2)*x + A(x/4)^2*x^2/2 + A(x/8)^3*x^3/3 + A(x/16)^4*x^4/4 +...

%o (PARI) {a(n)=local(A=1+x);for(n=2,n, A=exp(sum(k=1,n,subst(A,x,x/2^k+x*O(x^n))^k*x^k/k)));2^(n*(n-1)/2)*polcoeff(A,n)}

%Y Cf. A157675.

%K nonn

%O 0,3

%A _Paul D. Hanna_, May 02 2009

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.

Last modified August 7 07:35 EDT 2024. Contains 375008 sequences. (Running on oeis4.)