1,2

RRS of n means reduced residue system modulo n. One considers here the smallest positive one. - Wolfdieter Lang, Jan 16 2016

Antti Karttunen, Table of n, a(n) for n = 1..10000

a(n) = n - A045763(n) = d(n) + phi(n) - 1 = A000005(n) + A000010(n) - 1.

If p is prime then a(p) = p.

Row sums of triangle A134673. - Gary W. Adamson, Nov 05 2007

DivisorSigma[0, #] + EulerPhi[#] - 1 & /@ Range[73] (* Jayanta Basu, Jul 09 2013 *)

(PARI) a(n)=my(f=factor(n)); numdiv(f)+eulerphi(f)-1 \\ Charles R Greathouse IV, Nov 14 2014

Cf. A000004, A000010, A045763, A134673.

Sequence in context: A094802 A075084 A086593 * A088468 A049448 A130044

Adjacent sequences: A073754 A073755 A073756 * A073758 A073759 A073760

nonn

Labos Elemer, Aug 08 2002

approved