

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
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OFFSET

0,3


LINKS

Diana L. Mecum, Table of n, a(n) for n = 0..1199


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 * A083260 A284011 A275468
Adjacent sequences: A119652 A119653 A119654 * A119656 A119657 A119658


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



