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!)
A158265 G.f.: A(x) = exp( Sum_{n>=1} 2*sigma(n,n+1)*x^n/n ). 0

%I #2 Mar 30 2012 18:37:16

%S 1,2,11,74,697,8002,115158,1949640,38662510,872245634,22150393253,

%T 623661939852,19296665400632,650198159192554,23700604926216759,

%U 928939297013294294,38956230043045053042,1740248411222193973416

%N G.f.: A(x) = exp( Sum_{n>=1} 2*sigma(n,n+1)*x^n/n ).

%C Definition: sigma(n,n+1) = Sum_{d|n} d^(n+1): [1,9,82,1057,15626,...].

%e G.f.: A(x) = 1 + 2*x + 11*x^2 + 74*x^3 + 697*x^4 + 8002*x^5 +...

%e log(A(x)) = 2*x + 18*x^2/2 + 164*x^3/3 + 2114*x^4/4 + 31252*x^5/5 +...

%o (PARI) a(n)=polcoeff(exp(sum(m=1, n, 2*sigma(m, m+1)*x^m/m)+x*O(x^n)), n)

%Y Cf. A158095, A023881.

%K nonn

%O 0,2

%A _Paul D. Hanna_, Mar 29 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.

License Agreements, Terms of Use, Privacy Policy. .

Last modified March 28 20:05 EDT 2024. Contains 371254 sequences. (Running on oeis4.)