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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 (list; graph; refs; listen; history; text; internal format)
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[30n-30, 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

Juri-Stepan Gerasimov, Jul 06 2008

EXTENSIONS

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

STATUS

approved

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Last modified September 15 14:36 EDT 2019. Contains 327078 sequences. (Running on oeis4.)