OFFSET
1,10
COMMENTS
Preprimes of k-th kind are defined in comment in A247395.
LINKS
Indranil Ghosh, Table of n, a(n) for n = 1..10000
Vladimir Shevelev , A classification of the positive integers over primes
FORMULA
EXAMPLE
If n = 15, then, by the formula, we have a(15) = 2 - 2 + 1 = 1.
MATHEMATICA
Table[If[n==1 || PrimeQ[n], 0, PrimePi[Sqrt[n]] - PrimePi[FactorInteger[n][[1, 1]]] + 1], {n, 1, 125}] (* Indranil Ghosh, Mar 08 2017 *)
PROG
(PARI) for(n=1, 125, print1(if(n==1 || isprime(n), 0, primepi(sqrt(n)) - primepi(vecmin(factor(n)[, 1])) + 1), ", ")) \\ Indranil Ghosh, Mar 08 2017
CROSSREFS
KEYWORD
nonn,look
AUTHOR
Vladimir Shevelev, Sep 28 2014
STATUS
approved