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Least prime factor of n
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n |
By convention, 1 is given as its own least prime factor, but of course this has met with objections. By disallowing 1 as a prime number, we can then say that each prime number is its own least and greatest prime factor. However, in the OEIS, it is reasonable to believe that some users will look up the sequence of least prime factors as “1, 2, 3, 2, 5, 2, 7, 2, 3, 2 ” (give or take a few terms), and that should deliver a result.
Sequences
Smallest prime dividingn, n ≥ 2, |
Lpf (n) |
a (1) = 1 |
- {2, 3, 2, 5, 2, 7, 2, 3, 2, 11, 2, 13, 2, 3, 2, 17, 2, 19, 2, 3, 2, 23, 2, 5, 2, 3, 2, 29, 2, 31, 2, 3, 2, 5, 2, 37, 2, 3, 2, 41, 2, 43, 2, 3, 2, 47, 2, 7, 2, 3, 2, 53, 2, 5, 2, 3, 2, 59, 2, ...}
See also
- p-smooth numbers
- Largest prime dividing n
- A006530 Gpf (n): greatest prime factor of n (greatest prime dividing n), with
.a (1) = 1
- p-rough numbers
- Smallest prime dividing n
- A020639
: least prime factor of n (least prime dividing n), withLpf (n)
.a (1) = 1