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A023568
Number of distinct prime divisors of prime(n)-3.
3
0, 0, 1, 1, 1, 2, 2, 1, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 1, 2, 3, 2, 2, 2, 2, 2, 2, 2, 2, 3, 2, 1, 2, 2, 2, 2, 3, 2, 2, 3, 2, 2, 2, 3, 2, 2, 2, 3, 2, 2, 3, 2, 3, 2, 2, 3, 3, 2, 2, 2, 3, 3, 2, 3, 3, 2, 2, 2, 2, 2, 3, 2, 3, 3, 2, 3, 2, 2, 2, 3, 2, 3, 2, 3, 2, 3, 2, 2, 2, 3, 2, 3, 2, 2, 2, 2, 3, 3, 3
OFFSET
1,6
COMMENTS
a(n) = 1 if prime(n) is in A057733. - Robert Israel, Dec 28 2015
LINKS
MAPLE
0, 0, seq(nops(numtheory:-factorset(ithprime(i)-3)), i=3..100); # Robert Israel, Dec 28 2015
MATHEMATICA
Join[{0, 0}, PrimeNu/@(Prime[Range[3, 100]]-3)] (* Harvey P. Dale, Sep 09 2017 *)
CROSSREFS
Sequence in context: A332992 A337788 A346510 * A081753 A332999 A334144
KEYWORD
nonn
STATUS
approved