A292048 - OEIS

%I #10 Sep 15 2017 02:55:54

%S 2,30,35070,36570,43230,159810,224610,331170,525630,1039890,1094730,

%T 1290810,1656930,1770510,2139990,4878390,5110710,5996310,6052530,

%U 6127890,7493430,9918930,10146570,12171810,12551370,13821870,21398370,23282130,25587030,30223830,31317510,31364970

%N Squarefree numbers n such that psi(phi(n)) = phi(psi(n) - n).

%e 30 = 2*3*5 is a term because psi(phi(30)) = phi(psi(30)-30).

%e 60 = 30*2 is not a term because it is not a squarefree number.

%o (PARI) a001615(n) = my(f=factor(n)); prod(i=1, #f~, f[i, 1]^f[i, 2] + f[i, 1]^(f[i, 2]-1));

%o isok(n) = issquarefree(n) && a001615(eulerphi(n))==eulerphi(a001615(n)-n); \\ after _Charles R Greathouse IV_ at A001615

%Y Cf. A000010, A001615, A290002.

%K nonn

%O 1,1

%A _Altug Alkan_, Sep 08 2017