OFFSET
1,2
LINKS
G. C. Greubel, Table of n, a(n) for n = 1..770
EXAMPLE
1, 9/8, 259/216, 1063/864, 136331/108000, 15259/12000, ...
MAPLE
with(numtheory); seq(numer(add(phi(k)/k^3, k = 1..n)), n = 1..25); # G. C. Greubel, Aug 26 2019
MATHEMATICA
Numerator[Table[Sum[EulerPhi[k]/k^3, {k, n}], {n, 20}]] (* Harvey P. Dale, May 27 2012 *)
PROG
(PARI) a(n) = numerator( sum(k=1, n, eulerphi(k)/k^3)); \\ G. C. Greubel, Aug 26 2019
(Magma) [Numerator( &+[EulerPhi(k)/k^3: k in [1..n]] ): n in [1..25]]; // G. C. Greubel, Aug 26 2019
(Sage) [numerator( sum(euler_phi(k)/k^3 for k in (1..n)) ) for n in (1..25)] # G. C. Greubel, Aug 26 2019
(GAP) List([1..25], n-> NumeratorRat( Sum([1..n], k-> Phi(k)/k^3) ) ); # G. C. Greubel, Aug 26 2019
CROSSREFS
KEYWORD
nonn,frac
AUTHOR
N. J. A. Sloane, Jun 28 2002
STATUS
approved