OFFSET
1,2
FORMULA
a(n) ~ 6*n^5 / (5*Pi^2). - Vaclav Kotesovec, May 22 2021
MATHEMATICA
a[n_] := Sum[k^3 * EulerPhi[k], {k, 1, n}]; Array[a, 40] (* Amiram Eldar, May 22 2021 *)
Accumulate[Table[k^3*EulerPhi[k], {k, 1, 40}]] (* Vaclav Kotesovec, May 22 2021 *)
PROG
(PARI) a(n) = sum(k=1, n, k^3*eulerphi(k));
CROSSREFS
KEYWORD
nonn
AUTHOR
Seiichi Manyama, May 22 2021
STATUS
approved