A128267 a(0) = 1; a(n) = gcd((number of earlier terms which are coprime to n), (sum of the earlier terms which are coprime to n)).

1, 1, 2, 1, 3, 1, 4, 1, 2, 1, 1, 1, 8, 1, 2, 1, 1, 1, 12, 1, 2, 1, 1, 1, 16, 1, 2, 5, 1, 1, 19, 1, 1, 1, 1, 1, 2, 1, 3, 1, 1, 1, 2, 1, 1, 1, 1, 1, 1, 1, 2, 1, 2, 1, 1, 1, 1, 1, 1, 1, 2, 1, 2, 2, 2, 1, 1, 1, 1, 6, 1, 1, 2, 1, 1, 1, 8, 11, 8, 1, 2, 1, 12, 1, 1, 1, 9

Offset

0,3

Links

Diana L. Mecum, Table of n, a(n) for n = 0..1677

Example

The terms among {a(0),a(1),...,a(7)} that are coprime to 8 are a(0)=1, a(1)=1, a(3)=1, a(4)=3, a(5)=1 and a(7)=1. There are 6 such terms and the sum of these terms is 8. So a(8) = gcd(6,8) = 2.

Crossrefs

Cf. A128268.

Sequence in context: A177812 A280504 A087267 * A289508 A364448 A028920

Adjacent sequences: A128264 A128265 A128266 * A128268 A128269 A128270

Keyword

nonn

Author

Leroy Quet, Feb 22 2007

Extensions

More terms from Diana L. Mecum, Aug 06 2012

Status

approved