A270265 - OEIS

%I #18 Dec 01 2024 04:08:40

%S 1936,3872,6348,7744,9196,15004,15488,18392,20812,21160,22264,30008,

%T 35332,36784,38416,41624,42320,44528,51304,58564,63916,65596,70664,

%U 73084,73568,76832,79420,81796,82668,83248,84100,84640,86152,96040,102124,102608,109384,110836

%N Numbers that are values of the totient function (A002202) but not of the reduced totient function (A002174).

%H Amiram Eldar, <a href="/A270265/b270265.txt">Table of n, a(n) for n = 1..10000</a>

%H William D. Banks, John B. Friedlander, Florian Luca, Francesco Pappalardi, and Igor E. Shparlinski, <a href="http://dx.doi.org/10.4064/aa122-3-1">Coincidences in the values of the Euler and Carmichael functions</a>, Acta Arithmetica 122 (2006), 207-234.

%o (PARI) isA002174(n) = if(n%2, return(n==1)); my(f=factor(n), pe); for(i=1, #f~, if(n%(f[i, 1]-1)==0, next); pe=f[i, 1]^f[i, 2]; forstep(q=2*pe+1, n+1, 2*pe, if(n%(q-1)==0 && isprime(q), next(2))); return(0)); 1 \\ _Charles R Greathouse IV_ at A002174

%o is(n) = istotient(n) && !isA002174(n); \\ _Amiram Eldar_, Nov 30 2024

%Y Cf. A000010, A002202.

%Y Cf. A002322, A002174.

%Y Cf. A270266.

%K nonn

%O 1,1

%A _Michel Marcus_, Mar 14 2016

%E More terms from _Jinyuan Wang_, Feb 13 2020