A140887 Number of nonprimes in [30n - 30, 30n] coprime to 30.

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

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: A076225 A215776 A339085 * 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