OFFSET
1,2
COMMENTS
MATHEMATICA
f[1] = 1; f[n_] := f[n] = Plus @@ (f /@ Most @ Divisors[n]); Select[Range[1000], f[#] == EulerPhi[#] &] (* Amiram Eldar, Feb 29 2020 *)
CROSSREFS
KEYWORD
nonn,more
AUTHOR
Juri-Stepan Gerasimov, Oct 08 2009
EXTENSIONS
Index in the definition corrected, and extended by R. J. Mathar, Oct 10 2009
a(18)-a(35) from Amiram Eldar, Feb 29 2020
STATUS
approved