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!)
A342621 Sum of the partition number of the prime factors of n with multiplicity. 1

%I #25 Apr 09 2021 19:51:39

%S 0,2,3,4,7,5,15,6,6,9,56,7,101,17,10,8,297,8,490,11,18,58,1255,9,14,

%T 103,9,19,4565,12,6842,10,59,299,22,10,21637,492,104,13,44583,20,

%U 63261,60,13,1257,124754,11,30,16,300,105,329931,11,63,21,493,4567,831820

%N Sum of the partition number of the prime factors of n with multiplicity.

%H Alois P. Heinz, <a href="/A342621/b342621.txt">Table of n, a(n) for n = 1..10000</a> (first 3000 terms from Eric Desbiaux)

%F a(A003586(n)) - A001414(A003586(n)) = 0.

%F a(A006899(n)) * A008480(A006899(n)) - A001414(A006899(n)) = 0.

%F a(n) = Sum_{k=1..A001222(n)} A000041(A027746(n,k)). - _Alois P. Heinz_, Apr 09 2021

%e For n = 408 = 2^3*3*17, a(408) = 3 * A000041(2) + A000041(3) + A000041(17) = 3*2 + 3 + 297 = 306.

%p a:= n-> add(combinat[numbpart](i[1])*i[2], i=ifactors(n)[2]):

%p seq(a(n), n=1..70); # _Alois P. Heinz_, Mar 17 2021

%t {0}~Join~Array[Total@ Map[#2 PartitionsP[#1] & @@ # &, FactorInteger[#]] &, 58, 2] (* _Michael De Vlieger_, Mar 17 2021 *)

%o (Sage)

%o def a(n):

%o return sum([Partitions(primefactor).cardinality() for (primefactor,exponent) in factor(n) for _ in range(exponent)])

%o [a(n) for n in (1..100)]

%o (PARI) a(n) = my(f=factor(n)); sum(k=1, #f~, f[k,2]*numbpart(f[k,1])); \\ _Michel Marcus_, Mar 17 2021

%Y Cf. A000041, A027746, A058698, A001222.

%K nonn

%O 1,2

%A _Eric Desbiaux_, Mar 16 2021

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 25 01:06 EDT 2024. Contains 371964 sequences. (Running on oeis4.)