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

 

Logo
Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A176720 G.f. satisfies: A(x) = 1 + Sum_{n>=0} 2*x^(n^2)*A(x)^n. 1

%I #2 Mar 30 2012 18:37:21

%S 1,2,4,8,18,44,112,288,744,1938,5104,13584,36456,98468,267376,729488,

%T 1999074,5500412,15189636,42084952,116949848,325878288,910333152,

%U 2548892864,7152113760,20108587038,56641227416,159820928328

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

%e G.f.: A(x) = 1 + 2*x + 4*x^2 + 8*x^3 + 18*x^4 + 44*x^5 + 112*x^6 +...

%e A(x) = 1 + 2*x*A(x) + 2*x^4*A(x)^2 + 2*x^9*A(x)^3 + 2*x^16*A(x)^4 + ...

%o (PARI) {a(n)=local(A=1+x);for(i=1,n,A=1+sum(m=1,n,2*(A+x*O(x^n))^m*x^(m^2)));polcoeff(A,n)}

%Y Cf. A157134, A176719.

%K nonn

%O 0,2

%A _Paul D. Hanna_, Apr 25 2010

%E Edited by _Paul D. Hanna_, Apr 27 2010

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.

License Agreements, Terms of Use, Privacy Policy. .

Last modified April 24 22:17 EDT 2024. Contains 371964 sequences. (Running on oeis4.)