OFFSET
1,1
COMMENTS
The terms are ordered according to their lesser counterparts (A307051).
a(17) > 4*10^12. - Giovanni Resta, Mar 24 2019
MATHEMATICA
f[p_, e_] := p^e + (-1)^e; a[1] = 1; a[n_] := Times @@ f @@@ FactorInteger[n]; s={}; Do[m = a[n]; If[m > n && a[m] == n, AppendTo[s, m]], {n, 1, 10^7}]; s
CROSSREFS
KEYWORD
nonn,more
AUTHOR
Amiram Eldar, Mar 21 2019
EXTENSIONS
a(16) from Giovanni Resta, Mar 24 2019
STATUS
approved