OFFSET
1,2
COMMENTS
MATHEMATICA
aQ[n_] := Divisible[Numerator[Plus @@ ((1/Select[Range[n], CoprimeQ[n, #] &])^2)], n^2]; Select[Range[10^4], aQ]
PROG
(PARI) isok(m) = !(numerator(sum(k=1, m, if (gcd(k, m) == 1, 1/k^2))) % m^2); \\ Michel Marcus, Aug 13 2019
(Magma) v:= [Numerator(&+[1/k^2:k in [1..n]|Gcd(k, n) eq 1]):n in [1..10000]]; [m:m in [1..#v]| v[m] mod m^2 eq 0]; // Marius A. Burtea, Aug 14 2019
CROSSREFS
KEYWORD
nonn
AUTHOR
Amiram Eldar and Thomas Ordowski, Aug 13 2019
STATUS
approved