OFFSET
1,1
COMMENTS
Phi(.)= A000010(.) is the Euler totient function.
REFERENCES
J.-M. De Koninck, Ces nombres qui nous fascinent, Entry 410, p. 91, Ellipses, Paris 2008.
LINKS
Donovan Johnson, Table of n, a(n) for n = 1..500
H. Fripertinger, The Euler phi function
Wikipedia, Euler's totient function
FORMULA
41n < a(n) <= 205 * 2^n. - Charles R Greathouse IV, May 15 2013
EXAMPLE
For n = 410, phi(410)/410 = 160/410 = 16/41, which puts 410 into the sequence.
MAPLE
with(numtheory): ii:=1: N0:=40: tabl:=array(1..N0+1): for n from 1 to 540000 do : if 41*phi(n)=16*n then tabl[ii]:= n: ii:= ii+1: fi: od: print(tabl):
PROG
(PARI) is(n)=eulerphi(n)/n==16/41 \\ Charles R Greathouse IV, May 15 2013
CROSSREFS
KEYWORD
nonn
AUTHOR
Michel Lagneau, Apr 21 2010
EXTENSIONS
Link to b-file of another sequence removed - R. J. Mathar, Oct 20 2010
STATUS
approved