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Squarefree kernel of 2*prime(n)+1.
2

%I #11 Sep 07 2020 06:29:53

%S 5,7,11,15,23,3,35,39,47,59,21,15,83,87,95,107,119,123,15,143,21,159,

%T 167,179,195,203,69,215,219,227,255,263,55,93,299,303,105,327,335,347,

%U 359,33,383,129,395,399,141,447,455,51,467,479,483,503

%N Squarefree kernel of 2*prime(n)+1.

%H Amiram Eldar, <a href="/A072058/b072058.txt">Table of n, a(n) for n = 1..10000</a>

%F a(n) = A007947(A072055(n)).

%e n = 12: 2*A000040(12)+1 = 2*37+1 = 75 and as A007947(75) = A007947(7*5*5) = 15: a(12) = 15.

%t rad[n_] := Times @@ FactorInteger[n][[;;,1]]; rad /@ (2 * Select[Range[250], PrimeQ] + 1) (* _Amiram Eldar_, Sep 07 2020 *)

%Y Cf. A000040, A007947, A072055.

%K nonn

%O 1,1

%A _Reinhard Zumkeller_, Jun 11 2002