|
|
A062401
|
|
a(n) = phi(sigma(n)).
|
|
103
|
|
|
1, 2, 2, 6, 2, 4, 4, 8, 12, 6, 4, 12, 6, 8, 8, 30, 6, 24, 8, 12, 16, 12, 8, 16, 30, 12, 16, 24, 8, 24, 16, 36, 16, 18, 16, 72, 18, 16, 24, 24, 12, 32, 20, 24, 24, 24, 16, 60, 36, 60, 24, 42, 18, 32, 24, 32, 32, 24, 16, 48, 30, 32, 48, 126, 24, 48, 32, 36, 32, 48, 24, 96, 36, 36, 60
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
1,2
|
|
REFERENCES
|
D. S. Mitrinovic et al., Handbook of Number Theory, Kluwer, p. 14.
|
|
LINKS
|
|
|
FORMULA
|
|
|
EXAMPLE
|
a(9) = 12 because sigma(9) = 13 and phi(13) = 12.
|
|
MAPLE
|
|
|
MATHEMATICA
|
Table[EulerPhi[DivisorSigma[1, n]], {n, 1, 80}] (* Carl Najafi, Aug 16 2011 *)
|
|
PROG
|
(PARI) vector(150, n, eulerphi(sigma(n)))
(PARI) for (n=1, 10000, write("b062401.txt", n, " ", eulerphi(sigma(n))) ) \\ Harry J. Smith, Aug 07 2009
(Haskell)
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
|
|
STATUS
|
approved
|
|
|
|