OFFSET
1,3
COMMENTS
Compare the definition of a(n) to phi(n) = number of integers in {1, 2, ..., n} that are coprime to n.
EXAMPLE
There are four integers in {1, 2, ..., Fibonacci(5) = 5} that are coprime to 5, i.e. 1, 2, 3, 4. Hence a(5) = 4.
MATHEMATICA
h[n_] := Module[{l}, l = {}; For[i = 1, i <= Fibonacci[n], i++, If[GCD[i, n] == 1, l = Append[l, i]]]; l]; Table[Length[h[i]], {i, 1, 21}]
Table[Count[Range[Fibonacci[n]], _?(CoprimeQ[#, n]&)], {n, 25}] (* Harvey P. Dale, Oct 31 2011 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Joseph L. Pe, Oct 04 2002
EXTENSIONS
More terms from Harvey P. Dale, Oct. 31 2011
a(26)-a(41) from Donovan Johnson, Nov 03 2011
STATUS
approved