OFFSET
2,1
COMMENTS
If it is not 0, a(30) > 10^30. - Michel Marcus, Sep 08 2018
LINKS
Yasutoshi Kohmoto, UnitaryPhi, SeqFan list, Aug 31 2018.
Michel Marcus, solve_uphi pari code
FORMULA
a(pp) = pp iff pp is a prime power (A000961) > 1.
PROG
(PARI) \\ uses the "solve_uphi pari code", see links
a(n) = {my(lim = 1, v); while (1, v = solve_uphi(n-1, n, lim); if (#v, return (v[1])); lim *= 10; ); }
CROSSREFS
KEYWORD
nonn,more
AUTHOR
Michel Marcus, Sep 04 2018
STATUS
approved