

A063070


a(n) = phi(n)  d(n), where d(n) is the number of divisors function (A000005).


8



0, 1, 0, 1, 2, 2, 4, 0, 3, 0, 8, 2, 10, 2, 4, 3, 14, 0, 16, 2, 8, 6, 20, 0, 17, 8, 14, 6, 26, 0, 28, 10, 16, 12, 20, 3, 34, 14, 20, 8, 38, 4, 40, 14, 18, 18, 44, 6, 39, 14, 28, 18, 50, 10, 36, 16, 32, 24, 56, 4, 58, 26, 30, 25, 44, 12, 64, 26, 40, 16, 68, 12, 70, 32, 34, 30, 56, 16, 76, 22, 49, 36, 80, 12, 60, 38, 52, 32, 86, 12, 68, 38
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OFFSET

1,5


COMMENTS

It is known that a(n) >= 1 for n >= 31.


REFERENCES

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


LINKS

T. D. Noe, Table of n, a(n) for n=1..1000


PROG

(PARI) j=[]; for(n=1, 150, j=concat(j, eulerphi(n)(numdiv(n)))); j
(PARI) { for (n=1, 1000, write("b063070.txt", n, " ", eulerphi(n)  numdiv(n)) ) } \\ Harry J. Smith, Aug 16 2009


CROSSREFS

Cf. A000010, A000005. A020488 gives n such that a(n) = 0.
Sequence in context: A246846 A292474 A127528 * A049802 A129240 A246816
Adjacent sequences: A063067 A063068 A063069 * A063071 A063072 A063073


KEYWORD

easy,sign


AUTHOR

Jason Earls, Aug 04 2001


STATUS

approved



