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!)
A328745 Dirichlet g.f.: Product_{p prime} 1 / (1 - p^(-s))^p. 1

%I

%S 1,2,3,3,5,6,7,4,6,10,11,9,13,14,15,5,17,12,19,15,21,22,23,12,15,26,

%T 10,21,29,30,31,6,33,34,35,18,37,38,39,20,41,42,43,33,30,46,47,15,28,

%U 30,51,39,53,20,55,28,57,58,59,45,61,62,42,7,65,66,67,51,69,70,71,24,73,74,45

%N Dirichlet g.f.: Product_{p prime} 1 / (1 - p^(-s))^p.

%C Number of ways to factor n into 2 kinds of 2, 3 kinds of 3, 5 kinds of 5, ... , p kinds of p.

%F If n = Product (p_j^k_j) then a(n) = Product (binomial(p_j + k_j - 1, k_j)).

%p a:= n-> mul(binomial(i[1]+i[2]-1, i[2]), i=ifactors(n)[2]):

%p seq(a(n), n=1..100); # _Alois P. Heinz_, Oct 26 2019

%t a[n_] := Times @@ (Binomial[#[[1]] + #[[2]] - 1, #[[2]]] & /@ FactorInteger[n]); Table[a[n], {n, 1, 75}]

%Y Cf. A008480, A050367, A059481, A135323, A182938.

%K nonn,mult

%O 1,2

%A _Ilya Gutkovskiy_, Oct 26 2019

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 15 10:18 EDT 2021. Contains 342977 sequences. (Running on oeis4.)