OFFSET
1,2
LINKS
Nathaniel Johnston, Table of n, a(n) for n = 1..2500
EXAMPLE
MAPLE
with(numtheory):
a := proc(n) return phi(n)*add(phi(k), k=1..n): end:
seq(a(n), n=1..46); # Nathaniel Johnston, Jun 26 2011
MATHEMATICA
a[n_]:= a[n]= EulerPhi[n]*Sum[EulerPhi[k], {k, n}];
Table[a[n], {n, 50}] (* G. C. Greubel, Sep 10 2024 *)
PROG
(PARI) a(n)=sum(k=1, n, eulerphi(k))*eulerphi(n) \\ Charles R Greathouse IV, Feb 21 2013
(Magma)
A143231:= func< n | EulerPhi(n)*(&+[EulerPhi(k): k in [1..n]]) >;
[A143231(n): n in [1..50]]; // G. C. Greubel, Sep 10 2024
(SageMath)
def A143231(n): return euler_phi(n)*sum(euler_phi(k) for k in range(1, n+1))
[A143231(n) for n in range(1, 51)] # G. C. Greubel, Sep 10 2024
CROSSREFS
KEYWORD
nonn
AUTHOR
Gary W. Adamson, Jul 31 2008
EXTENSIONS
Terms after a(14) from Nathaniel Johnston, Jun 26 2011
STATUS
approved