A037228 a(n) = phi(n) - pi(n).

1, 0, 0, 0, 1, -1, 2, 0, 2, 0, 5, -1, 6, 0, 2, 2, 9, -1, 10, 0, 4, 2, 13, -1, 11, 3, 9, 3, 18, -2, 19, 5, 9, 5, 13, 1, 24, 6, 12, 4, 27, -1, 28, 6, 10, 8, 31, 1, 27, 5, 17, 9, 36, 2, 24, 8, 20, 12, 41, -1, 42, 12, 18, 14, 30, 2, 47, 13, 25, 5, 50, 4, 51, 15, 19, 15, 39, 3, 56, 10, 32, 18, 59, 1, 41, 19

Offset: 1

Author

N. J. A. Sloane

Keywords

• sign

Comments

It is known that a(n) >= 0 for n >= 61.

References

• D. S. Mitrinovic et al., Handbook of Number Theory, Kluwer, p. 11.

Links

• Alois P. Heinz, Table of n, a(n) for n = 1..10000 (first 1000 terms from T. D. Noe)

Crossrefs

Cf. A000010, A000720, A037171, A037229.

Programs

Mathematica

Table[EulerPhi[n]-PrimePi[n],{n,90}] (* Harvey P. Dale, Feb 02 2021 *)

PARI

a(n) = eulerphi(n) - primepi(n); \\ Michel Marcus, Aug 08 2019