A072813 a(n)^A072814(n) is the n-th perfect power.

1, 2, 2, 3, 4, 5, 3, 2, 6, 7, 8, 9, 10, 11, 5, 2, 12, 13, 14, 6, 15, 3, 16, 17, 18, 7, 19, 20, 21, 22, 8, 23, 24, 25, 26, 27, 28, 29, 30, 31, 10, 32, 33, 34, 35, 36, 11, 37, 38, 39, 40, 41, 12, 42, 43, 44, 45, 2, 46, 3, 13, 47, 48, 49, 50, 51, 52, 14, 53, 54, 55, 5, 56, 57, 58, 15

Offset: 1

Author

Reinhard Zumkeller, Jul 12 2002

Keywords

• nonn

Links

• Eric Weisstein's World of Mathematics, Perfect Power.

Crossrefs

Cf. A001597(n) = a(n)^A072814(n).

Programs

Mathematica

{1}~Join~Map[Function[m, Function[w, 1 + Position[w, Min@ DeleteCases[w, x_ /; x < 2]][[1, 1]]]@ Table[Boole[k^# == m] # &@ IntegerExponent[m, k], {k, 2, Floor@ Sqrt@ m}]], Select[Range@ 3400, GCD @@ FactorInteger[#][[All, -1]] > 1 &]] (* Michael De Vlieger, Dec 08 2016 *)

Extensions

Inserted a(1) = 1 by Gionata Neri, Dec 08 2016