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!)
A339396 Number of partitions of n into an odd number of nonprime parts. 1

%I #4 Dec 02 2020 20:59:09

%S 0,1,0,1,1,1,2,1,3,3,4,4,6,6,9,9,13,14,18,20,26,29,37,39,51,57,69,78,

%T 95,105,129,141,173,192,231,255,306,340,403,446,531,585,691,764,896,

%U 995,1160,1279,1493,1652,1911,2117,2443,2700,3109,3434,3941,4357,4983,5496,6277

%N Number of partitions of n into an odd number of nonprime parts.

%H <a href="/index/Par#part">Index entries for sequences related to partitions</a>

%F G.f.: (1/2) * (Product_{k>=1} (1 - x^prime(k)) / (1 - x^k) - Product_{k>=1} (1 + x^prime(k)) / (1 + x^k)).

%F a(n) = (A002095(n) - A302236(n)) / 2.

%e a(9) = 3 because we have [9], [4, 4, 1] and [1, 1, 1, 1, 1, 1, 1, 1, 1].

%t nmax = 60; CoefficientList[Series[(1/2) (Product[(1 - x^Prime[k])/(1 - x^k), {k, 1, nmax}] - Product[(1 + x^Prime[k])/(1 + x^k), {k, 1, nmax}]), {x, 0, nmax}], x]

%Y Cf. A002095, A018252, A027193, A184199, A302236, A339381, A339395.

%K nonn

%O 0,7

%A _Ilya Gutkovskiy_, Dec 02 2020

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 23 13:04 EDT 2024. Contains 371913 sequences. (Running on oeis4.)