login
a(n) = smallest integer which is coprime to n and is > A057237(n).
1

%I #11 Aug 12 2015 21:09:57

%S 2,3,4,3,6,5,8,3,4,3,12,5,14,3,4,3,18,5,20,3,4,3,24,5,6,3,4,3,30,7,32,

%T 3,4,3,6,5,38,3,4,3,42,5,44,3,4,3,48,5,8,3,4,3,54,5,6,3,4,3,60,7,62,3,

%U 4,3,6,5,68,3,4,3,72,5,74,3,4,3,8,5,80,3

%N a(n) = smallest integer which is coprime to n and is > A057237(n).

%C a(n) is also the smallest positive integer m, m > 1, which is coprime to n where (m-1) is not coprime to n.

%e The integers which are coprime to 9 are 1,2,4,5,7,8,10,11,13,14,... Now 1 and 2, but not 3, are coprime to 9, so A057237(9) = 2. The smallest integer > 2 and coprime to 9 is 4. So a(9) = 4.

%p A020639 := proc(n) if n = 1 then 1 ; else min(op(numtheory[divisors](n) minus {1})) ; fi ; end: A057237 := proc(n) if n = 1 then 1 ; else A020639(n)-1 ; fi: end: A126801 := proc(n) local a; for a from A057237(n)+1 do if gcd(n,a) = 1 then RETURN(a) ; fi ; od: end: seq(A126801(n),n=1..80) ; # _R. J. Mathar_, Nov 01 2007

%Y Cf. A057237.

%K nonn

%O 1,1

%A _Leroy Quet_, Feb 21 2007

%E More terms from _R. J. Mathar_, Nov 01 2007