A037228: pi - phi
Alonso Del Arte
alonso.delarte at gmail.com
Mon Oct 3 19:38:40 CEST 2005
I'm a little confused about the comment for A037228, I'm wondering if
I'm reading it wrong (I might be getting confused about the direction
of greater than and less than signs). It says: "It is known that a(n)
>= 0 for n >= 61." For example, pi(61) - phi(61) = -42, which is
clearly less than zero. But pi(62) - phi(62) = -12. In fact, the
Mathematica command
Select[Range[10000], (PrimePi[#] - EulerPhi[#]) < 0 &]
gives you almost all the first 10000 integers. The skipped integers
are {2, 3, 4, 6, 8, 10, 12, 14, 18, 20, 24, 30, 42, 60, 90} (listed in
A037229).
Alonso
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