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

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A181588 G.f. satisfies: A(x) = 1 + x*Sum_{n>=0} log( A(2^n*x) )^n/(2^n*n!). 0

%I

%S 1,1,1,3,28,658,36336,4918960,1913308480,2722820397008,

%T 16147361055588096,383879833447290828032,34790330152647391683716096,

%U 11818617432918372433417869737472

%N G.f. satisfies: A(x) = 1 + x*Sum_{n>=0} log( A(2^n*x) )^n/(2^n*n!).

%F a(n+1) = [x^n] A(x)^(2^(n-1)) for n>=0, with a(0)=1, where A(x) = Sum_{n>=0} a(n)*x^n.

%e G.f.: A(x) = 1 + x + x^2 + 3*x^3 + 28*x^4 + 658*x^5 + 36336*x^6 +...

%e A(x) = 1 + x*[1 + log(A(2x))/2 + log(A(4x))^2/(4*2!) + log(A(8x))^3/(8*3!) + log(A(16x))^4/(16*4!) +...].

%e Coefficients in the 2^n-th powers of A(x) begin:

%e A^(2^0)=[1,(1), 1, 3, 28, 658, 36336, 4918960, 1913308480,...];

%e A^(2^1)=[1, 2,(3), 8, 63, 1378, 74053, 9912076, 3836532284,...];

%e A^(2^2)=[1, 4, 10,(28), 167, 3056, 154060, 20129640, 7713183207,...];

%e A^(2^3)=[1, 8, 36, 136,(658), 8008, 336692, 41562232, 15590683759,...];

%e A^(2^4)=[1, 16, 136, 848, 4788,(36336), 867384, 89267088,...];

%e A^(2^5)=[1, 32, 528, 6048, 55208, 456544,(4918960), 224294304,...];

%e A^(2^6)=[1, 64, 2080, 45888, 776272, 10833088, 133934688,(1913308480), ...]; ...

%e where the diagonal terms in parenthesis form this sequence (shift left).

%o (PARI) {a(n)=local(A=[1, 1]); for(i=1, n, A=concat(A, Vec(Ser(A)^(2^(#A-2)))[ #A])); A[n+1]}

%Y Cf. A132695, A181444.

%K nonn

%O 0,4

%A _Paul D. Hanna_, Nov 03 2010

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 October 15 00:14 EDT 2019. Contains 328025 sequences. (Running on oeis4.)