OFFSET
0,4
EXAMPLE
The positive integers which are <= 12 and are coprime to 12 are 1,5,7,11. Dividing each of these by 2 and rounding down, we get 0,2,3,5. So a(12) = a(0) + a(2) + a(3) + a(5) = 1+1+2+4 = 8.
MATHEMATICA
a = {1}; For[n = 1, n < 70, n++, s = 0; b = Select[Range[n], GCD[n, # ] == 1 &]; For[j = 1, j < Length[b] + 1, j++, s = s + a[[Floor[b[[j]]/2] + 1]]]; AppendTo[a, s]]; a (* Stefan Steinerberger, Nov 20 2007 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Leroy Quet, Nov 17 2007
EXTENSIONS
More terms from Stefan Steinerberger, Nov 20 2007
STATUS
approved