A372599 Number of distinct prime factors of n^n-n.

1, 2, 3, 4, 4, 5, 4, 6, 5, 6, 5, 9, 5, 6, 12, 8, 4, 10, 5, 11, 7, 6, 7, 12, 8, 13, 8, 10, 6, 14, 8, 12, 9, 10, 18, 18, 6, 11, 11, 19, 8, 16, 5, 12, 13, 7, 7, 20, 5, 18, 12, 14, 7, 21, 12, 19, 10, 10, 7, 24, 7, 10, 20, 15, 13, 19, 6, 19, 11, 19, 9, 25, 6, 13

Offset

2,2

Links

Table of n, a(n) for n=2..75.

Formula

a(n) = A001221(A061190(n)).

Mathematica

a[n_] := a[n] = PrimeNu[n^n - n];
Table[a[n], {n, 2, 75}] (* Robert P. P. McKone, May 07 2024 *)

Prog

(PARI) a(n) = omega(n^n-n);
(Python)
from sympy.ntheory.factor_ import primenu
def A372599(n): return primenu(n*(n**(n-1)-1)) # Chai Wah Wu, May 07 2024

Crossrefs

Cf. A001221, A061190, A372546, A372229, A344870, A344869.

Sequence in context: A306574 A088527 A343400 * A030602 A133947 A082090

Adjacent sequences: A372596 A372597 A372598 * A372600 A372601 A372602

Keyword

nonn

Author

Tyler Busby, May 06 2024

Status

approved