A292048 Squarefree numbers n such that psi(phi(n)) = phi(psi(n) - n).

2, 30, 35070, 36570, 43230, 159810, 224610, 331170, 525630, 1039890, 1094730, 1290810, 1656930, 1770510, 2139990, 4878390, 5110710, 5996310, 6052530, 6127890, 7493430, 9918930, 10146570, 12171810, 12551370, 13821870, 21398370, 23282130, 25587030, 30223830, 31317510, 31364970

Offset: 1

Author

Altug Alkan, Sep 08 2017

Keywords

• nonn

Examples

			30 = 2*3*5 is a term because psi(phi(30)) = phi(psi(30)-30).
60 = 30*2 is not a term because it is not a squarefree number.
		

Crossrefs

Cf. A000010, A001615, A290002.

Programs

PARI

a001615(n) = my(f=factor(n)); prod(i=1, #f~, f[i, 1]^f[i, 2] + f[i, 1]^(f[i, 2]-1));
isok(n) = issquarefree(n) && a001615(eulerphi(n))==eulerphi(a001615(n)-n); \\ after Charles R Greathouse IV at A001615