A097606 a(n) = number of terms among {a(1), a(2), a(3), ..., a(n-1)} that are coprime to n; a(1)=6.

6, 0, 0, 0, 1, 1, 3, 3, 2, 4, 7, 3, 9, 6, 5, 8, 13, 5, 15, 8, 9, 12, 19, 7, 18, 13, 13, 14, 25, 8, 27, 18, 17, 18, 24, 12, 33, 19, 16, 17, 37, 13, 39, 24, 20, 25, 43, 18, 42, 22, 25, 23, 49, 21, 42, 27, 28, 32, 55, 16, 57, 34, 30, 34, 47, 22, 63, 34, 38, 24, 67, 24, 69, 37, 35, 37

Offset

1,1

Comments

Numbers not present: 10, 11, 29, 31, 36, 41, 48, 51, 54, 58, 62, 65, 68, ...,. - Robert G. Wilson v, Sep 03 2004

Links

Table of n, a(n) for n=1..76.

Maple

A family of related sequences can be generated using different positive integers for a(1). (a(1)=1 gives sequence A096216.)

Mathematica

a[1] = 6; a[n_] := a[n] = Count[ GCD[n, Table[ a[i], {i, n - 1}]], 1]; Table[ a[n], {n, 76}] (* Robert G. Wilson v, Sep 03 2004 *)

Crossrefs

Cf. A096216.

Sequence in context: A089804 A270606 A087255 * A201995 A226784 A281319

Adjacent sequences: A097603 A097604 A097605 * A097607 A097608 A097609

Keyword

nonn

Author

Leroy Quet, Aug 30 2004

Extensions

More terms from Robert G. Wilson v, Sep 03 2004

Status

approved