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!)
A333701 Number of ways to write n as the sum of two positive integers with the same number of distinct prime factors. 2
0, 1, 0, 1, 1, 2, 2, 2, 2, 3, 3, 4, 3, 3, 3, 5, 2, 5, 3, 6, 5, 5, 2, 7, 4, 6, 6, 7, 4, 9, 4, 10, 6, 11, 6, 12, 3, 9, 7, 11, 6, 10, 6, 10, 9, 12, 5, 14, 7, 14, 8, 12, 6, 16, 8, 15, 10, 14, 8, 18, 10, 15, 10, 16, 8, 20, 9, 18, 14, 17, 10, 23, 12, 18, 15, 17 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,6

LINKS

Table of n, a(n) for n=1..76.

Index entries for sequences related to partitions

FORMULA

a(n) = Sum_{i=1..floor(n/2)} [omega(i) = omega(n-i)], where [] is the Iverson bracket and omega is the number of distinct prime factors of n (A001221).

MATHEMATICA

Table[Sum[KroneckerDelta[PrimeNu[i], PrimeNu[n - i]], {i, Floor[n/2]}], {n, 100}]

CROSSREFS

Cf. A001221, A333708 (distinct numbers).

Sequence in context: A024366 A218123 A288157 * A140682 A049317 A134544

Adjacent sequences:  A333698 A333699 A333700 * A333702 A333703 A333704

KEYWORD

nonn,easy

AUTHOR

Wesley Ivan Hurt, Apr 02 2020

STATUS

approved

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 May 18 23:31 EDT 2022. Contains 353826 sequences. (Running on oeis4.)