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!)
A320244 G.f.: Product_{k>=1, j>=1} (1 + x^(k*j))^2 / (1 - x^(k*j)). 1
1, 3, 10, 28, 72, 172, 397, 867, 1840, 3783, 7580, 14829, 28454, 53540, 99119, 180676, 324758, 576145, 1010051, 1750782, 3003386, 5101769, 8586891, 14327582, 23711567, 38937304, 63471475, 102741924, 165204561, 263956121, 419183458, 661833319, 1039140705 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

COMMENTS

Convolution of A006171 and A320235.

LINKS

Vaclav Kotesovec, Table of n, a(n) for n = 0..10000

FORMULA

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

MATHEMATICA

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

CROSSREFS

Cf. A006171, A320235, A320238.

Sequence in context: A062431 A034351 A182737 * A128135 A191797 A027252

Adjacent sequences:  A320241 A320242 A320243 * A320245 A320246 A320247

KEYWORD

nonn

AUTHOR

Vaclav Kotesovec, Oct 08 2018

STATUS

approved

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 April 9 10:52 EDT 2020. Contains 333348 sequences. (Running on oeis4.)