Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 61st year, we have over 378,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”).
%I #10 Dec 08 2016 11:31:31
%S 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,
%T 21,22,8,23,24,25,26,27,28,29,30,31,10,32,33,34,35,36,11,37,38,39,40,
%U 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
%N a(n)^A072814(n) is the n-th perfect power.
%H Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/PerfectPower.html">Perfect Power</a>.
%t {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 *)
%Y Cf. A001597(n) = a(n)^A072814(n).
%K nonn
%O 1,2
%A _Reinhard Zumkeller_, Jul 12 2002
%E Inserted a(1) = 1 by _Gionata Neri_, Dec 08 2016