A130700 a(0)=1; a(n) is the n-th integer from among those positive integers which are coprime to (a(n-1)*n).

1, 1, 3, 4, 7, 6, 17, 8, 15, 16, 23, 12, 35, 19, 33, 31, 33, 29, 55, 27, 73, 37, 49, 27, 71, 31, 57, 43, 67, 30, 109, 32, 63, 64, 71, 51, 113, 38, 79, 62, 103, 42, 145, 56, 111, 88, 105, 106, 145, 73, 127

Offset: 0

Author

Leroy Quet, Aug 12 2007

Keywords

• nonn
• look

Examples

			a(8)*9 = 135. Those positive integers which are coprime to 135 form the sequence: 1,2,4,7,8,11,13,14,16,17,19,22,... The 9th of these integers is 16, so a(9) = 16.
		

Links

• Robert Israel, Table of n, a(n) for n = 0..10000

Crossrefs

Cf. A069213.

Programs

Maple

a[0]:=1: for n to 50 do CP:={}: for j while nops(CP)<=n do if gcd(n*a[n-1],j) =1 then CP:=`union`(CP,{j}) else end if end do: a[n]:=CP[n] end do: seq(a[n], n=0..50); # Emeric Deutsch, Aug 28 2007

Extensions

More terms from Emeric Deutsch, Aug 28 2007