A076397 - OEIS

%I #12 Feb 16 2025 08:32:47

%S 1,2,2,3,2,5,3,2,3,7,2,3,5,11,5,2,3,13,7,3,5,3,2,17,3,7,19,5,7,11,2,

%T 23,3,5,13,3,7,29,5,31,5,2,11,17,7,3,11,37,19,13,5,41,3,7,43,11,5,2,

%U 23,3,13,47,3,7,5,17,13,7,53,3,11,5,7,19,29,5,59,5,61,31,7,2,13,11,67,17,23

%N Largest prime factor of n-th perfect power.

%C a(n) = A006530(A001597(n)).

%H Reinhard Zumkeller, <a href="/A076397/b076397.txt">Table of n, a(n) for n = 1..10000</a>

%H Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/PerfectPower.html">Perfect Powers</a>.

%H Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/GreatestPrimeFactor.html">Greatest Prime Factor</a>.

%F a(n) = A006530(A025478(n)).

%t perfPQ[n_]:=GCD@@FactorInteger[n][[All,2]]>1; Join[ {1},FactorInteger[ #][[-1,1]]&/@ Select[Range[5000],perfPQ]] (* _Harvey P. Dale_, Sep 12 2021 *)

%o (Haskell)

%o a076397 = a006530 . a025478 -- _Reinhard Zumkeller_, Mar 28 2014

%Y Cf. A025478, A076396, A076403.

%K nonn

%O 1,2

%A _Reinhard Zumkeller_, Oct 09 2002