login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A320236 G.f.: Product_{k>=1, j>=1} 1/(1 - x^(k*j))^2. 5

%I

%S 1,2,7,16,41,86,193,384,787,1504,2899,5338,9852,17586,31330,54490,

%T 94350,160370,271171,451776,748460,1225106,1993860,3212378,5146851,

%U 8175114,12915747,20252564,31595134,48964310,75515995,115777684,176696336,268231986,405436258

%N G.f.: Product_{k>=1, j>=1} 1/(1 - x^(k*j))^2.

%C Self-convolution of A006171.

%H Vaclav Kotesovec, <a href="/A320236/b320236.txt">Table of n, a(n) for n = 0..10000</a>

%F Conjecture: log(a(n)) ~ Pi * sqrt(2*n*log(n)/3).

%t nmax = 50; CoefficientList[Series[Product[1/(1-x^(k*j))^2, {k, 1, nmax}, {j, 1, Floor[nmax/k] + 1}], {x, 0, nmax}], x]

%Y Cf. A006171, A004101, A320235.

%K nonn

%O 0,2

%A _Vaclav Kotesovec_, Oct 08 2018

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 January 26 16:58 EST 2020. Contains 331280 sequences. (Running on oeis4.)