OFFSET
1,1
LINKS
Charles R Greathouse IV, Table of n, a(n) for n = 1..10000
Ivars Peterson, The Amazing ABC Conjecture
M. Waldschmidt, Open Diophantine problems, arXiv:math/0312440 [math.NT], 2003-2004.
Eric Weisstein's World of Mathematics, ABC Conjecture
Eric Weisstein's World of Mathematics, Squarefree
Wikipedia, abc conjecture
EXAMPLE
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.
MATHEMATICA
sfk[n_] := Times @@ FactorInteger[n][[All, 1]];
a[n_] := sfk[n Prime[n] (n+Prime[n])];
Array[a, 40] (* Jean-François Alcover, Feb 04 2019 *)
PROG
(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
(Haskell)
a066197 n = a007947 $ a033286 n * a014688 n
-- Reinhard Zumkeller, Jul 24 2013
CROSSREFS
KEYWORD
nonn
AUTHOR
Reinhard Zumkeller, Dec 15 2001
STATUS
approved