OFFSET
1,3
EXAMPLE
Among the 15 earliest terms of the sequence there are 3 terms not divisible by exactly one distinct prime, as 16 is. (These 3 terms are 1, 1 {both divisible by 0 primes} and 14 {divisible by 2 distinct primes}.) So a(16) = 3.
MATHEMATICA
a = {1}; For[n = 2, n < 70, n++, c = 0; For[j = 1, j < Length[a] + 1, j++, If[Not[Length[FactorInteger[a[[j]]]] == Length[FactorInteger[n]]], c++ ]]; AppendTo[a, c]]; a (* Stefan Steinerberger, Nov 21 2007 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Leroy Quet, Dec 28 2005
EXTENSIONS
More terms from Stefan Steinerberger, Nov 21 2007
STATUS
approved