OFFSET
1,3
EXAMPLE
The sum of the distinct prime divisors of 12 is 2+3 = 5. So a(12) is the number of terms from among (a(1),a(2),...a(11)) which are coprime to 5. There are 9 such terms, so a(12) = 9.
MATHEMATICA
g[l_List] := Block[{n = Length[l] + 1}, Append[l, Count[GCD[l, f[n]], 1]]]; Nest[g, {1}, 75] (* Ray Chandler, Mar 26 2007 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Leroy Quet, Mar 16 2007
EXTENSIONS
Extended by Ray Chandler, Mar 26 2007
STATUS
approved