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A125296 a(1)=1. a(n) is the number of earlier terms of the sequence which are noncomposites (1 or primes) and are coprime to n. 0
1, 1, 2, 2, 4, 2, 5, 3, 6, 3, 8, 3, 9, 6, 5, 7, 11, 6, 12, 7, 8, 9, 13, 8, 12, 10, 11, 10, 15, 7, 16, 13, 12, 14, 12, 11, 18, 15, 13, 14, 19, 11, 21, 14, 16, 18, 21, 15, 18, 16, 18, 15, 21, 15, 15, 15, 17, 19, 23, 16, 24, 21, 18, 21, 19, 15, 25, 21, 21, 17, 26, 20, 26, 23, 22, 21, 20 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

LINKS

Table of n, a(n) for n=1..77.

EXAMPLE

The noncomposites among the first 7 terms of the sequence are 1,1,2,2,2,5. Of these, three terms (1,1,5) are coprime to 8. So a(8)=3.

MATHEMATICA

f[l_List] := Append[l, Length[Select[l, GCD[ #, Length[l] + 1] == 1 && (PrimeQ[ # ] || # == 1) &]]]; Nest[f, {1}, 80] (*Chandler*)

CROSSREFS

Sequence in context: A129296 A300837 A321443 * A294097 A233520 A243271

Adjacent sequences:  A125293 A125294 A125295 * A125297 A125298 A125299

KEYWORD

nonn

AUTHOR

Leroy Quet, Dec 08 2006

EXTENSIONS

Extended by Ray Chandler, Dec 11 2006

STATUS

approved

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Last modified September 20 12:32 EDT 2019. Contains 327235 sequences. (Running on oeis4.)