OFFSET
0,3
LINKS
Alois P. Heinz, Table of n, a(n) for n = 0..10000
FORMULA
a(n) = A005598(n) - 1.
G.f.: (1/(1 - x)^2)*Sum_{k>=1} mu(k)*x^k/(1 - x^k)^2. - Ilya Gutkovskiy, Mar 16 2017
MAPLE
b:= proc(n) option remember; `if`(n<1, [0$2],
(p-> p+[numtheory[phi](n), p[1]])(b(n-1)))
end:
a:= n-> b(n+1)[2]:
seq(a(n), n=0..55); # Alois P. Heinz, Oct 07 2021
MATHEMATICA
Accumulate@Accumulate@EulerPhi@Range[0, 100] (* Vladimir Joseph Stephan Orlovsky, Apr 21 2011 *)
PROG
(Magma)
A103116:= func< n | n eq 0 select 0 else (&+[(n-j+1)*EulerPhi(j): j in [1..n]]) >;
[A103116(n): n in [0..60]]; // G. C. Greubel, Dec 08 2022
(SageMath)
@CachedFunction
def A103116(n): return sum( (n-j+1)*euler_phi(j) for j in range(1, n+1) )
[A103116(n) for n in range(61)] # G. C. Greubel, Dec 08 2022
CROSSREFS
KEYWORD
nonn
AUTHOR
N. J. A. Sloane, Apr 04 2007
STATUS
approved