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 May 19 2017 14:32:38
%S 1,2,3,2,5,2,7,2,3,3,11,2,13,3,3,2,17,2,19,3,4,4,23,2,5,5,3,3,29,3,31,
%T 2,5,5,5,2,37,6,6,3,41,3,43,4,3,6,47,2,7,3,7,5,53,2,7,3,7,7,59,3,61,7,
%U 4,2,8,4,67,5,8,4,71,2,73,8,3,6,8,4,79,3
%N Integer part of the geometric mean of the prime factors of n.
%H G. C. Greubel, <a href="/A276632/b276632.txt">Table of n, a(n) for n = 1..5000</a>
%F a(n) = floor( A007947(n)^(1/A001221(n)) ).
%e For n=20, the two distinct prime factors are 2 and 5, the arithmetic mean is sqrt(2*5), and the integer part is a(20)=3.
%p A276632 := proc(n)
%p floor(root[A001221(n)](A007947(n))) ;
%p end proc:
%p seq(A276632(n),n=1..80) ;
%t rad[n_] := Times @@ (First@# & /@ FactorInteger@n); Table[Floor[(rad[n])^(1/PrimeNu[n])], {n, 1, 50}] (* _G. C. Greubel_, May 19 2017 *)
%Y Cf. A079866 (primes with multiplicity)
%K nonn
%O 1,2
%A _R. J. Mathar_, Sep 08 2016