OFFSET
1,2
MATHEMATICA
Module[{nmax = 20, a = {}, p = 1, f}, Do[p *= p + 1; f = 2; While[MemberQ[a, f] || !Divisible[p, f], f = NextPrime[f]]; AppendTo[a, f], nmax]; PrimePi[a]] (* Paolo Xausa, Sep 09 2024 *)
CROSSREFS
KEYWORD
nonn,more
AUTHOR
Peter Luschny, Sep 05 2024
STATUS
approved