OFFSET
1,3
COMMENTS
The asymptotic density of numbers k such that a(k) <= m for a given m is 0 (Dressler, 1974). - Amiram Eldar, Mar 02 2021
LINKS
Charles R Greathouse IV, Table of n, a(n) for n = 1..10000
Robert E. Dressler, On a theorem of Niven, Canadian Mathematical Bulletin, Vol. 17, No. 1 (1974), pp. 109-110.
MATHEMATICA
Table[GCD[DivisorSigma[1, n], EulerPhi[n]], {n, 110}] (* Harvey P. Dale, Aug 10 2011 *)
PROG
(PARI) a(n)=gcd(sigma(n=factor(n)), eulerphi(n)) \\ Charles R Greathouse IV, Nov 27 2013
(Haskell)
a009223 n = gcd (a000203 n) (a000010 n)
-- Reinhard Zumkeller, Jan 19 2014
CROSSREFS
KEYWORD
nonn
AUTHOR
STATUS
approved