

A140887


Number of nonprimes in [30n  30, 30n] coprime to 30.


1



1, 1, 1, 2, 3, 2, 3, 2, 3, 3, 4, 2, 3, 4, 2, 3, 3, 6, 3, 3, 3, 2, 4, 4, 4, 3, 5, 2, 4, 4, 4, 4, 4, 3, 3, 4, 2, 5, 5, 4, 3, 4, 4, 2, 6, 5, 5, 3, 4, 1, 6, 3, 4, 2, 5, 4, 4, 5, 4, 4, 5, 6, 1, 5, 5, 5, 3, 3, 5, 3, 5, 3, 6, 5, 4, 4, 3, 5, 4, 1, 5, 4, 5, 7, 3, 5, 5, 5, 4, 1, 3, 4, 5, 3, 5, 4, 4, 5, 4, 6, 4, 5, 3, 6, 6
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OFFSET

1,4


COMMENTS

For almost all n, a(n) = phi(30) = 8. It first attains this value at a(361).


LINKS

Table of n, a(n) for n=1..105.


EXAMPLE

{1,7,11,13,17,19,23,29} are coprime to 30 in [0, 30]; 1 is nonprime, so a(1) = 1.
{31,37,41,43,47,49,53,59} are coprime to 30 in [30, 60]; 49 is nonprime, so a(2) = 1.


MATHEMATICA

Table[Count[Range[30n30, 30n], _?(CoprimeQ[#, 30]&&!PrimeQ[#]&)], {n, 110}] (* Harvey P. Dale, Oct 04 2012 *)


CROSSREFS

Cf. A007775.
Sequence in context: A105528 A076225 A215776 * A132423 A071995 A114108
Adjacent sequences: A140884 A140885 A140886 * A140888 A140889 A140890


KEYWORD

nonn,easy,less


AUTHOR

JuriStepan Gerasimov, Jul 06 2008


EXTENSIONS

Rewritten and extended by Charles R Greathouse IV, Mar 26 2010


STATUS

approved



