A188525 - OEIS

%I #31 Mar 17 2023 07:11:25

%S 2,5,10,5,26,37,10,5,10,101,122,37,170,197,226,5,290,37,362,101,442,

%T 485,530,37,26,677,10,197,842,901,962,5,1090,1157,1226,37,1370,85,

%U 1522,101,58,1765,370,485,226,2117,2210,37,10,101,2602,677,2810,37

%N a(n) = rad(rad(n)^2+1), where rad = A007947.

%H Charles R Greathouse IV, <a href="/A188525/b188525.txt">Table of n, a(n) for n = 1..10000</a>

%F a(n) = A007947(A078615(n)+1). - _R. J. Mathar_, Apr 04 2011

%e a(7) = rad(rad(7)^2 + 1) = rad(7^2 + 1) = rad(50) = 10.

%p with(numtheory):

%p rad:= n-> mul(i, i=factorset(n)):

%p a:= n-> rad(rad(n)^2+1):

%p seq(a(n), n=1..70);  # _Alois P. Heinz_, Apr 03 2011

%t rad[n_] := Times @@ FactorInteger[n][[All, 1]];

%t a[n_] := rad[rad[n]^2 + 1];

%t Array[a, 70] (* _Jean-François Alcover_, Mar 27 2017 *)

%o (Magma) [ &*PrimeDivisors((&*PrimeDivisors(n))^2+1): n in [1..51] ]; // _Bruno Berselli_, Apr 04 2011

%o (PARI) rad(n)=my(f=factor(n)[,1]);prod(i=1,#f,f[i])

%o a(n)=rad(rad(n)^2+1) \\ _Charles R Greathouse IV_, Aug 08 2013

%Y Cf. A007947, A078322.

%K nonn,easy

%O 1,1

%A _Jonathan Vos Post_, Apr 03 2011