A345674 - OEIS

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A345674

Euler totient function phi(n) - number of primitive roots modulo n.

0, 0, 1, 1, 2, 1, 4, 4, 4, 2, 6, 4, 8, 4, 8, 8, 8, 4, 12, 8, 12, 6, 12, 8, 12, 8, 12, 12, 16, 8, 22, 16, 20, 8, 24, 12, 24, 12, 24, 16, 24, 12, 30, 20, 24, 12, 24, 16, 30, 12, 32, 24, 28, 12, 40, 24, 36, 16, 30, 16, 44, 22, 36, 32, 48, 20, 46, 32, 44, 24

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,5

LINKS

Table of n, a(n) for n=1..70.

FORMULA

a(n) = A000010(n) - A046144(n).

MAPLE

a:= proc(n) uses numtheory; `if`(n=1, 0, (p->

p-add(`if`(order(i, n)=p, 1, 0), i=0..n-1))(phi(n)))

end:

seq(a(n), n=1..70); # Alois P. Heinz, Jun 22 2021