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A023575
Number of distinct prime divisors of prime(n)+3.
3
1, 2, 1, 2, 2, 1, 2, 2, 2, 1, 2, 2, 2, 2, 2, 2, 2, 1, 3, 2, 2, 2, 2, 2, 2, 2, 2, 3, 2, 2, 3, 2, 3, 2, 2, 3, 2, 2, 3, 2, 3, 2, 2, 2, 2, 2, 2, 2, 3, 2, 2, 2, 2, 2, 3, 3, 2, 2, 3, 2, 3, 2, 3, 2, 2, 2, 2, 3, 3, 2, 2, 2, 3, 2, 2, 2, 2, 2, 2, 2, 2, 2, 3, 2, 3, 2, 2, 3, 2, 2, 3, 2, 3, 3, 2, 3, 1, 2, 2
OFFSET
1,2
LINKS
FORMULA
a(n) = omega(prime(n)+3). - Wesley Ivan Hurt, Mar 06 2022
MAPLE
f:= proc(p) nops(numtheory:-factorset(p+3)) end proc:
map(f, [seq(ithprime(i), i=1..100)]); # Robert Israel, Mar 06 2022
MATHEMATICA
a[n_] := PrimeNu[Prime[n]+3]; Array[a, 100] (* Amiram Eldar, Sep 29 2024 *)
PROG
(PARI) a(n) = omega(prime(n)+3); \\ Amiram Eldar, Sep 29 2024
CROSSREFS
Cf. A000040 (prime), A001221 (omega).
Sequence in context: A183028 A114284 A238303 * A215113 A058978 A105446
KEYWORD
nonn,easy
STATUS
approved