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A001598 Number of terms in {b(1)..b(n)} relatively prime to b(n), where b(n) = A001597(n).
(Formerly M2244 N0891)
1
1, 1, 1, 3, 2, 5, 5, 4, 2, 9, 5, 8, 5, 13, 12, 8, 5, 17, 8, 6, 11, 14, 11, 23, 7, 23, 26, 11, 16, 14, 15, 31, 10, 28, 16, 24, 15, 37, 9, 39, 16, 20, 27, 20, 31, 14, 43, 47, 23, 32, 20, 51, 17, 14, 54, 24, 30, 28, 27, 40, 57, 61, 20, 56, 26, 42, 30, 28, 68, 22 (list; graph; refs; listen; history; text; internal format)
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

Sequence in context: A132778 A182289 A127738 * A141297 A303917 A186929

Adjacent sequences:  A001595 A001596 A001597 * A001599 A001600 A001601

KEYWORD

nonn,easy

AUTHOR

N. J. A. Sloane.

EXTENSIONS

a(1) added by T. D. Noe, Aug 09 2012

STATUS

approved

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Last modified January 20 14:02 EST 2020. Contains 331094 sequences. (Running on oeis4.)