OFFSET
1,1
LINKS
Charles R Greathouse IV, Table of n, a(n) for n = 1..10000
FORMULA
EXAMPLE
a(7) = rad(rad(7)^2 + 1) = rad(7^2 + 1) = rad(50) = 10.
MAPLE
with(numtheory):
rad:= n-> mul(i, i=factorset(n)):
a:= n-> rad(rad(n)^2+1):
seq(a(n), n=1..70); # Alois P. Heinz, Apr 03 2011
MATHEMATICA
rad[n_] := Times @@ FactorInteger[n][[All, 1]];
a[n_] := rad[rad[n]^2 + 1];
Array[a, 70] (* Jean-François Alcover, Mar 27 2017 *)
PROG
(Magma) [ &*PrimeDivisors((&*PrimeDivisors(n))^2+1): n in [1..51] ]; // Bruno Berselli, Apr 04 2011
(PARI) rad(n)=my(f=factor(n)[, 1]); prod(i=1, #f, f[i])
a(n)=rad(rad(n)^2+1) \\ Charles R Greathouse IV, Aug 08 2013
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Jonathan Vos Post, Apr 03 2011
STATUS
approved