OFFSET
1,2
LINKS
Amiram Eldar, Table of n, a(n) for n = 1..1000
FORMULA
a(n) = f(A121556(n)), where f(m) = A000203(m)^2/(A034448(m)*A047994(m)). - Amiram Eldar, Dec 11 2019
MATHEMATICA
f[p_, e_] := (p^(e+1)-1)^2/(p-1)^2/(p^(2*e)-1); ratio[1] = 1; ratio[n_] := Times @@ (f @@@ FactorInteger[n]); Select[ratio /@ Range[10^5], IntegerQ] (* Amiram Eldar, Dec 11 2019 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Yasutoshi Kohmoto Sep 12 2006
EXTENSIONS
Extended with the aid of b121556.txt. - R. J. Mathar, Sep 04 2018
STATUS
approved