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URL: https://oeis.org/A103858

⇱ A103858 - OEIS

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A103858
Number of distinct prime factors of prime(n)! - prime(n)# + 1.
4
0, 0, 2, 1, 2, 2, 2, 2, 4, 2, 3, 4, 4, 5, 5, 3, 5, 3, 4, 6, 5, 4, 5, 6, 9, 1, 4
OFFSET
1,3
COMMENTS
a(27) >= 4. - Amiram Eldar, Jan 21 2024
FORMULA
a(n) = A001221(A103855(n)).
MATHEMATICA
primorial[n_] := Product[Prime[i], {i, n}]; A103855[n_] := Prime[n]! - primorial[n] + 1; PrimeNu[Array[A103855, 20]] (* G. C. Greubel, May 09 2017 *)
PROG
(PARI) a(n) = omega(prime(n)! - prod(k=1, n, prime(k)) + 1); \\ Michel Marcus, Nov 06 2022
CROSSREFS
KEYWORD
nonn,more
AUTHOR
Reinhard Zumkeller, Feb 20 2005
EXTENSIONS
a(27) from Jinyuan Wang, Jun 19 2025
STATUS
approved