1,3

The positive integers that are <=10 and are coprime to 10 are 1,3,7,9. LCM(1,3,7,9) = 63. Now the positive integers that are coprime to 10 form a sequence that begins: 1,3,7,9,11,13,17,19,21,23,27,29,31,33,37,39,41,43,47,49,51,53,57,59,61,63,67,69,...

Since 63 is the 26th of these integers, then a(10) = 26.

Cf. A038610.

Sequence in context: A135816 A038036 A133631 this_sequence A083457 A127058 A094359

Adjacent sequences: A137447 A137448 A137449 this_sequence A137451 A137452 A137453

more,nonn

Leroy Quet (q1qq2qqq3qqqq(AT)yahoo.com), Apr 18 2008