A066695 Numbers k such that Euler phi(k) / Carmichael lambda(k) = 12.

252, 273, 315, 364, 399, 468, 481, 532, 546, 630, 651, 665, 684, 693, 741, 756, 777, 793, 798, 855, 868, 903, 945, 949, 962, 988, 1001, 1036, 1071, 1085, 1116, 1204, 1209, 1261, 1281, 1287, 1302, 1330, 1332, 1386, 1395, 1404, 1407, 1417, 1449, 1463

Offset: 1

Author

Randall L Rathbun, Jan 12 2002

Keywords

• easy
• nonn

Links

• Amiram Eldar, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A000010, A002322.

Continuation of A062373, A062374, A062375, A062376, A062377.

Programs

Mathematica

Select[Range[2000], EulerPhi[#]/CarmichaelLambda[#] == 12 &] (* Alonso del Arte, Apr 17 2017 *)

PARI

{cmf(f)=if( ((f[1]==2)&&(f[2]>2)),eulerphi(f[1]^f[2])/2, eulerphi(f[1]^f[2])) }
{cl(f)= k=factor(f); l=1; for(x=1,omega(f),l=lcm(l,cmf([k[x,1], k[x,2]]))); l }
{A0(n)=eulerphi(n)/cl(n)}
for(x=1,10001, if(A0(x)==12,print1(x, ",")))

PARI

isok(k) = eulerphi(k)/lcm(znstar(k)[2]) == 12; \\ Michel Marcus, May 25 2022