OFFSET
1
COMMENTS
After a(1) = 1 numbers such that only primes occur as exponents in their prime factorization.
LINKS
FORMULA
EXAMPLE
For n = 4 = 2^2, 2 is prime, thus a(4) = 1.
For n = 12 = 2^2 * 3^1, 2 is prime, but 1 is not, thus a(12) = 0.
For n = 16 = 2^4, 4 is not prime, thus a(16) = 0.
For n = 72 = 2^3 * 3^2, both exponents 3 and 2 are primes, thus a(72) = 1.
MATHEMATICA
{1}~Join~Array[Boole[AllTrue[FactorInteger[#][[All, -1]], PrimeQ]] &, 104, 2] (* Michael De Vlieger, Nov 17 2017 *)
PROG
CROSSREFS
KEYWORD
nonn,mult
AUTHOR
Antti Karttunen, Nov 17 2017
STATUS
approved