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A126630 a(1)=1. a(n) = the number of earlier terms that are coprime to the n-th Fibonacci number. 0
1, 1, 2, 3, 4, 3, 6, 4, 4, 9, 10, 2, 12, 13, 6, 9, 16, 7, 18, 10, 7, 21, 22, 3, 22, 25, 12, 15, 28, 11, 30, 15, 15, 33, 26, 7, 36, 37, 19, 12, 40, 19, 42, 24, 17, 45, 46, 9, 46, 36, 24, 27, 52, 22, 45, 22, 25, 57, 58, 10, 60, 61, 27, 30, 50, 30, 66, 35, 31, 41, 70, 10, 72, 73, 25, 41 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

LINKS

Table of n, a(n) for n=1..76.

EXAMPLE

The 8th Fibonacci number is 21. There are four terms from among the first 8 terms that are coprime to 21: a(1)=1, a(2)=1, a(3)=2 and a(5)=4. So a(8) = 4.

MAPLE

with(combinat): a:=proc(n) local ct, j: if n=1 then ct:=1: else ct:=0: for j from 1 to n-1 do if gcd(fibonacci(n), a(j))=1 then ct:=ct+1 else ct:=ct fi: od: fi: ct; end: seq(a(n), n=1..18); # Emeric Deutsch, Mar 23 2007

MATHEMATICA

a = {1}; Do[AppendTo[a, Length[Select[a, GCD[ #, Fibonacci[Length[a] + 1]] == 1 &]]], {80}]; a (* Stefan Steinerberger, Oct 16 2007 *)

CROSSREFS

Sequence in context: A117659 A079065 A097272 * A167234 A088043 A332931

Adjacent sequences:  A126627 A126628 A126629 * A126631 A126632 A126633

KEYWORD

nonn

AUTHOR

Leroy Quet, Mar 13 2007

EXTENSIONS

More terms from Emeric Deutsch, Mar 23 2007

More terms from Stefan Steinerberger, Oct 16 2007

STATUS

approved

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Last modified May 25 20:58 EDT 2020. Contains 334597 sequences. (Running on oeis4.)