OFFSET
1,2
LINKS
Amiram Eldar, Table of n, a(n) for n = 1..300 (terms 1..40 from Vincenzo Librandi)
EXAMPLE
k = 937248: phi(k) = 288000, phi(k+1) = 933120, 288000*933120 = 268738560000 = 720^4, so 937248 is here.
MATHEMATICA
f[x_] := EulerPhi[x]; Do[s=Sqrt[Sqrt[f[n+1]*f[n]]]; If[IntegerQ[s], Print[n]], {n, 1, 1000000}]
PROG
(PARI) isok(n) = ispower(eulerphi(n)*eulerphi(n+1), 4); \\ Michel Marcus, Jun 15 2017
CROSSREFS
KEYWORD
nonn
AUTHOR
Labos Elemer, May 21 2003
EXTENSIONS
a(29)-a(36) from Vincenzo Librandi, Jun 15 2017
STATUS
approved