1,2

The integers coprime to 1 are: 1,2,3,4,5,6,... The 5th of these is 5. The integers coprime to 2 are: 1,3,5,7,9,... The 4th of these is 7. The integers coprime to 3 are: 1,2,4,5,7,... The 3rd of these is 4. The integers coprime to 4 are: 1,3,5,... The 2nd of these is 3. And the integers coprime to 5 are: 1,2,3,4,6,... The 1st of these is 1. So a(5) = 5 * 7 * 4 * 3 * 1 = 420.

Cf. A132273, A132421.

Adjacent sequences: A130764 A130765 A130766 this_sequence A130768 A130769 A130770

Sequence in context: A056844 A002825 A052322 this_sequence A020698 A128752 A074611

more,nonn

Leroy Quet (qq-quet(AT)mindspring.com), Aug 18 2007