OFFSET
1,1
COMMENTS
a(n) is also the smallest positive integer m, m > 1, which is coprime to n where (m-1) is not coprime to n.
EXAMPLE
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.
MAPLE
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
CROSSREFS
KEYWORD
nonn
AUTHOR
Leroy Quet, Feb 21 2007
EXTENSIONS
More terms from R. J. Mathar, Nov 01 2007
STATUS
approved