A247176 Largest number of maximal order mod n.

0, 1, 2, 3, 3, 5, 5, 7, 5, 7, 8, 11, 11, 5, 13, 13, 14, 11, 15, 17, 19, 19, 21, 23, 23, 19, 23, 23, 27, 23, 24, 29, 29, 31, 33, 31, 35, 33, 37, 37, 35, 31, 34, 41, 43, 43, 45, 43, 47, 47, 46, 45, 51, 47, 53, 53, 53, 55, 56, 53, 59, 55, 61, 61, 63, 61, 63, 65, 67, 67, 69, 67

Offset: 1

Author

Eric Chen, Nov 29 2014

Keywords

• nonn
• easy

Examples

			a(18) = 11 because the largest possible order mod 18 is 6, and because 16, 15, 14, and 12 are not coprime to 18, and the orders of 17 and 13 to mod 18 are 2 and 3, not the largest possible order, and the order of 11 to mod 18 is 6, so a(18) = 11.
		

Links

• Eric Chen, Table of n, a(n) for n = 1..1000

Crossrefs

Cf. A002322 (orders), same as A046146 for n with primitive roots, A071894 (for primes).

Cf. A111076, A111725, A046145, A046144, A001918, A008330.

Programs

Mathematica

prms={}; f[n_] = Block[If[MultiplicativeOrder[p, n]=CarmichaelLambda[n], Join[prms, p]]; prms[-1]]; Array[f, 128]

PARI

carmichaellambda(n)=lcm(znstar(n)[2]);
for(i=1, 128, p=0; for(q=1, i-1, if(gcd(q, i)==1&&znorder(Mod(q, i))==carmichaellambda(i), p=q)); print1(p", "))

Extensions

a(68) corrected by Eric Chen, Jun 01 2015