OFFSET
1,2
LINKS
G. C. Greubel, Table of n, a(n) for n = 1..585
EXAMPLE
1, 17/16, 1409/1296, 11353/10368, 7137097/6480000, 7147097/6480000, ...
MAPLE
with(numtheory); seq(numer(add(phi(k)/k^4, k = 1..n)), n = 1..25); # G. C. Greubel, Aug 26 2019
MATHEMATICA
Table[Numerator[Sum[EulerPhi[k]/k^4, {k, n}]], {n, 25}] (* G. C. Greubel, Aug 26 2019 *)
Accumulate[Table[EulerPhi[n]/n^4, {n, 20}]]//Numerator (* Harvey P. Dale, Nov 15 2020 *)
PROG
(PARI) a(n) = numerator(sum(k=1, n, eulerphi(k)/k^4)); \\ G. C. Greubel, Aug 26 2019
(Magma) [Numerator( &+[EulerPhi(k)/k^4: k in [1..n]] ): n in [1..25]]; // G. C. Greubel, Aug 26 2019
(Sage) [numerator( sum(euler_phi(k)/k^4 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^4) ) ); # G. C. Greubel, Aug 26 2019
CROSSREFS
KEYWORD
nonn,frac
AUTHOR
N. J. A. Sloane, Jun 28 2002
STATUS
approved