A066695 - OEIS

%I #22 Dec 11 2024 00:37:45

%S 252,273,315,364,399,468,481,532,546,630,651,665,684,693,741,756,777,

%T 793,798,855,868,903,945,949,962,988,1001,1036,1071,1085,1116,1204,

%U 1209,1261,1281,1287,1302,1330,1332,1386,1395,1404,1407,1417,1449,1463

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

%H Amiram Eldar, <a href="/A066695/b066695.txt">Table of n, a(n) for n = 1..10000</a>

%t Select[Range[2000], EulerPhi[#]/CarmichaelLambda[#] == 12 &] (* _Alonso del Arte_, Apr 17 2017 *)

%o (PARI) {cmf(f)=if( ((f[1]==2)&&(f[2]>2)),eulerphi(f[1]^f[2])/2, eulerphi(f[1]^f[2])) }

%o {cl(f)= k=factor(f); l=1; for(x=1,omega(f),l=lcm(l,cmf([k[x,1], k[x,2]]))); l }

%o {A0(n)=eulerphi(n)/cl(n)}

%o for(x=1,10001, if(A0(x)==12,print1(x, ",")))

%o (PARI) isok(k) = eulerphi(k)/lcm(znstar(k)[2]) == 12; \\ _Michel Marcus_, May 25 2022

%Y Cf. A000010, A002322.

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

%K easy,nonn

%O 1,1

%A _Randall L Rathbun_, Jan 12 2002