A124218 a(n) is the m-th positive integer which is coprime to n, where phi(n) is number of positive integers which are <= n and are coprime to n, d(n) is the number of positive divisors of n and m = phi(n) if phi(n)|d(n), else m = d(n) mod phi(n).

1, 1, 2, 1, 2, 5, 2, 7, 4, 9, 2, 5, 2, 9, 7, 9, 2, 17, 2, 13, 5, 7, 2, 23, 3, 7, 5, 13, 2, 29, 2, 11, 5, 7, 4, 25, 2, 7, 5, 19, 2, 25, 2, 13, 11, 7, 2, 29, 3, 13, 5, 11, 2, 23, 4, 17, 5, 7, 2, 43, 2, 7, 10, 13, 4, 25, 2, 11, 5, 23, 2, 35, 2, 7, 11, 11, 4, 25, 2, 23, 7, 7, 2, 41, 4, 7, 5, 17, 2, 43, 4

Offset

1,3

Links

Antti Karttunen, Table of n, a(n) for n = 1..16384

Mathematica

f[n_] := Block[{k = 0, m = Mod[Length[Divisors[n]], EulerPhi[n], 1]}, While[m > 0, k++; While[GCD[n, k] > 1, k++ ]; m--; ]; k]; Table[f[n], {n, 100}] (* Ray Chandler, Oct 26 2006 *)

Prog

(PARI) A124218(n) = { my(d=numdiv(n), t=eulerphi(n), m=if(!(d%t), t, (d%t))); for(k=1, oo, if(1==gcd(k, n), m--; if(!m, return(k)))); }; \\ Antti Karttunen, Mar 30 2021

Crossrefs

Cf. A000005, A000010, A124219, A124330.

Sequence in context: A064192 A284553 A216913 * A025165 A345278 A212431

Adjacent sequences: A124215 A124216 A124217 * A124219 A124220 A124221

Keyword

nonn

Author

Leroy Quet, Oct 19 2006

Extensions

Edited and extended by Ray Chandler, Oct 26 2006

Status

approved