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 A066197 #19 Feb 16 2025 08:32:45 %S A066197 6,30,30,154,110,1482,714,114,138,11310,14322,1554,3198,34314,43710, %T A066197 7314,38114,28914,109478,64610,144102,175538,202354,60342,59170, %U A066197 333502,40170,22470,436218,484770,622046,42706,768570,817598,239890,169422 %N A066197 Squarefree kernel of (n*prime(n))*(n+prime(n)). %H A066197 Charles R Greathouse IV, <a href="/A066197/b066197.txt">Table of n, a(n) for n = 1..10000</a> %H A066197 Ivars Peterson, <a href="http://www.maa.org/mathland/mathtrek_12_8.html">The Amazing ABC Conjecture</a> %H A066197 M. Waldschmidt, <a href="https://arxiv.org/abs/math/0312440">Open Diophantine problems</a>, arXiv:math/0312440 [math.NT], 2003-2004. %H A066197 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/abcConjecture.html">ABC Conjecture</a> %H A066197 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/Squarefree.html">Squarefree</a> %H A066197 Wikipedia, <a href="http://en.wikipedia.org/wiki/Abc_conjecture">abc conjecture</a> %F A066197 a(n) = A007947(A033286(n) * A014688(n)). %e A066197 For n=20 we have: A = n = 20, B = A000040(20) = 71, C = A + B = 20 + 71 = 91 and A*B*C = 129220 with squarefree kernel a(20) = 64610 = 2*5*7*13*71. %t A066197 sfk[n_] := Times @@ FactorInteger[n][[All, 1]]; %t A066197 a[n_] := sfk[n Prime[n] (n+Prime[n])]; %t A066197 Array[a, 40] (* _Jean-François Alcover_, Feb 04 2019 *) %o A066197 (PARI) a(n)=my(p=prime(n),f=vecsort(concat(concat(p, factor(n)[,1]), factor(n+p)[,1]),,8)~); prod(i=1,#f,f[i]) \\ _Charles R Greathouse IV_, Jul 23 2013 %o A066197 (Haskell) %o A066197 a066197 n = a007947 $ a033286 n * a014688 n %o A066197 -- _Reinhard Zumkeller_, Jul 24 2013 %K A066197 nonn %O A066197 1,1 %A A066197 _Reinhard Zumkeller_, Dec 15 2001