A069114 - OEIS

%I #16 Aug 20 2024 01:56:03

%S 1,2,1,6,10,3,1,2,22,7,30,1,10,42,46,13,58,15,66,70,2,78,82,22,6,1,

%T 102,106,3,7,14,130,34,138,37,6,39,2,166,43,178,5,190,3,1,22,210,222,

%U 226,57,58,238,15,10,1,262,67,30,69,70,282,73,34,310,78,79,330,21,346,87

%N Squarefree part of prime(n)-1 : the smallest number such that a(n)*(prime(n)-1) is a square.

%H Amiram Eldar, <a href="/A069114/b069114.txt">Table of n, a(n) for n = 1..10000</a>

%F a(n) = A007913(A006093(n)). - _Amiram Eldar_, Sep 03 2020

%t core[n_] := Times @@ (First[#]^Mod[Last[#], 2]& /@ FactorInteger[n]); core /@ (Select[Range[350], PrimeQ] - 1) (* _Amiram Eldar_, Sep 03 2020 *)

%o (PARI) for(n=1,100,print1(core(prime(n)-1),","))

%Y Cf. A006093, A007913, A069115.

%K easy,nonn

%O 1,2

%A _Benoit Cloitre_, Apr 06 2002