OFFSET
1,4
LINKS
Charles R Greathouse IV, Table of n, a(n) for n = 1..10000
EXAMPLE
phi(16) = 8. So a(16) is the number of divisors of 16 which are <= 8. There are 4 such divisors: 1, 2, 4, 8; so a(16) = 4.
MAPLE
with(numtheory): a:=proc(n) local div, ct, j: div:=divisors(n): ct:=0: for j from 1 to tau(n) do if div[j]<=phi(n) then ct:=ct+1 else ct:=ct: fi od: ct; end: seq(a(n), n=1..135); # Emeric Deutsch, Mar 31 2007
MATHEMATICA
Table[Length[Select[Divisors[n], # <= EulerPhi[n] &]], {n, 104}] (* Jayanta Basu, May 23 2013 *)
PROG
(PARI) a(n)=my(p=eulerphi(n)); #select(k->k<=p, divisors(n)) \\ Charles R Greathouse IV, Mar 05 2013
CROSSREFS
KEYWORD
nonn
AUTHOR
Leroy Quet, Mar 30 2007
EXTENSIONS
More terms from Emeric Deutsch, Mar 31 2007
STATUS
approved