OFFSET
1,2
COMMENTS
a(n) = n iff n is prime; a(2*n)<=n+1; a(4*p)=2*p for primes p>2: a(A001749(n))=A057860(A001749(n)). - Reinhard Zumkeller, Jan 11 2004
LINKS
Alois P. Heinz, Table of n, a(n) for n = 1..10000
EXAMPLE
a(30) = 11 since 30k+m can be prime if m = 2, 3 or 5 (once each with k = 0) or m = 1, 7, 11, 13, 17, 19, 23 or 29 (each for an infinite number of values of k).
MAPLE
with(numtheory):
a:= n-> phi(n)+nops(factorset(n)):
seq(a(n), n=1..100); # Alois P. Heinz, Jul 14 2016
MATHEMATICA
Table[EulerPhi[n] + PrimeNu[n], {n, 1, 100}] (* G. C. Greubel, May 13 2017 *)
PROG
(PARI) for(n=1, 100, print1(eulerphi(n) + omega(n), ", ")) \\ G. C. Greubel, May 13 2017
CROSSREFS
KEYWORD
nonn,look
AUTHOR
Henry Bottomley, Sep 08 2000
STATUS
approved