This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A072058 #11 Sep 07 2020 06:29:53 %S A072058 5,7,11,15,23,3,35,39,47,59,21,15,83,87,95,107,119,123,15,143,21,159, %T A072058 167,179,195,203,69,215,219,227,255,263,55,93,299,303,105,327,335,347, %U A072058 359,33,383,129,395,399,141,447,455,51,467,479,483,503 %N A072058 Squarefree kernel of 2*prime(n)+1. %H A072058 Amiram Eldar, <a href="/A072058/b072058.txt">Table of n, a(n) for n = 1..10000</a> %F A072058 a(n) = A007947(A072055(n)). %e A072058 n = 12: 2*A000040(12)+1 = 2*37+1 = 75 and as A007947(75) = A007947(7*5*5) = 15: a(12) = 15. %t A072058 rad[n_] := Times @@ FactorInteger[n][[;;,1]]; rad /@ (2 * Select[Range[250], PrimeQ] + 1) (* _Amiram Eldar_, Sep 07 2020 *) %Y A072058 Cf. A000040, A007947, A072055. %K A072058 nonn %O A072058 1,1 %A A072058 _Reinhard Zumkeller_, Jun 11 2002