OFFSET
1,4
REFERENCES
N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
LINKS
T. D. Noe, Table of n, a(n) for n = 1..1000
H. W. Gould, Problem H-170, Fib. Quart., 8 (1970), p. 268.
MATHEMATICA
nn = 10^4; t = Join[{1}, Union[Flatten[Table[n^i, {i, Prime[Range[PrimePi[Log[2, nn]]]]}, {n, 2, nn^(1/i)}]]]]; Table[Count[GCD[Take[t, n], t[[n]]], 1], {n, Length[t]}] (* T. D. Noe, Aug 09 2012 *)
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
EXTENSIONS
a(1) added by T. D. Noe, Aug 09 2012
STATUS
approved