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!)
A300982 Number of partitions of n into parts having the same number of prime divisors (counted with multiplicity) as n. 7
1, 1, 1, 1, 1, 2, 1, 3, 1, 1, 2, 6, 1, 9, 3, 2, 1, 17, 1, 23, 2, 4, 7, 40, 1, 7, 10, 1, 3, 87, 2, 111, 1, 17, 25, 21, 1, 219, 34, 34, 2, 336, 4, 413, 7, 2, 73, 614, 1, 87, 7, 103, 10, 1083, 1, 149, 3, 176, 206, 1850, 2, 2198, 281, 7, 1, 344, 18, 3630, 25, 479, 22, 5007, 1, 5861, 725, 13 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,6

LINKS

Alois P. Heinz, Table of n, a(n) for n = 0..1000

Index entries for sequences related to partitions

FORMULA

a(n) = [x^n] Product_{bigomega(k) = bigomega(n)} 1/(1 - x^k).

EXAMPLE

a(20) = 2 because we have [20] and [12, 8], where 20, 12 and 8 are numbers that are the product of exactly 3 (not necessarily distinct) primes.

MAPLE

with(numtheory):

a:= proc(m) option remember; local k, b; k, b:= bigomega(m),

      proc(n, i) option remember; `if`(n=0, 1, `if`(i<1, 0,

        b(n, i-1)+`if`(bigomega(i)=k, b(n-i, min(i, n-i)), 0)))

      end: b(m$2)

    end:

seq(a(n), n=0..80);  # Alois P. Heinz, Mar 17 2018

MATHEMATICA

Table[SeriesCoefficient[Product[1/(1 - Boole[PrimeOmega[k] == PrimeOmega[n]] x^k), {k, 1, n}], {x, 0, n}], {n, 0, 75}]

CROSSREFS

Cf. A001222, A300977, A300978, A300979, A300980, A300983.

Sequence in context: A297381 A051793 A065371 * A186007 A212623 A229214

Adjacent sequences:  A300979 A300980 A300981 * A300983 A300984 A300985

KEYWORD

nonn

AUTHOR

Ilya Gutkovskiy, Mar 17 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 15 04:46 EDT 2021. Contains 342975 sequences. (Running on oeis4.)