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A119655
a(0) = a(1) = 0. a(n) = number of earlier terms of the sequence which are not coprime to n.
1
0, 0, 2, 2, 4, 2, 6, 2, 8, 3, 9, 2, 12, 2, 12, 7, 13, 2, 16, 2, 16, 8, 18, 2, 22, 2, 23, 8, 24, 2, 27, 2, 26, 11, 27, 3, 32, 2, 29, 14, 30, 2, 38, 2, 35, 14, 36, 2, 42, 7, 39, 16, 41, 2, 46, 6, 45, 19, 43, 2, 51, 2, 44, 24, 46, 8, 57, 2, 50, 24, 55, 2, 61, 2, 53, 25, 55, 13, 64, 2, 60
OFFSET
0,3
LINKS
EXAMPLE
Among the first 20 terms of the sequence there are 8 terms which are not coprime to 21 - a(0)=0, a(1)=0, a(6)=6, a(9)=3, a(10)=9, a(12)=12, a(14)=12 and a(15)=7. So a(21) = 8.
MATHEMATICA
a = {0, 0}; Do[AppendTo[a, Length[Select[a, GCD[Length[a], # ] > 1 &]]], {70}]; a (* Stefan Steinerberger, Oct 16 2007 *)
CROSSREFS
Sequence in context: A118982 A129457 A275365 * A364949 A083260 A284011
KEYWORD
nonn
AUTHOR
Leroy Quet, Jul 28 2006
EXTENSIONS
More terms from Stefan Steinerberger, Oct 16 2007
More terms from Diana L. Mecum, Aug 15 2008
STATUS
approved