A332738 - OEIS

%I #7 Feb 22 2020 12:52:07

%S 5642,9758,15402,51051,72105,73815,113883,134805,149226,202895,270655,

%T 352495,443555,552958,627095,650845,831369,831831,841269,870870,

%U 881705,956242,1000110,1088255,1135290,1255110,1255215,1418395,1447095,1455762,1610070,1718717,1746955

%N Composite squarefree numbers k = Product_{i} p_i such that k^2 is divisible by Sum_{i} p_i^2.

%H Amiram Eldar, <a href="/A332738/b332738.txt">Table of n, a(n) for n = 1..1000</a>

%e 5642 = 2 * 7 * 13 * 31 is a term since 5642^2/(2^2 + 7^2 + 13^2 + 31^2) = 26908 is an integer.

%t Select[Range[10^6], CompositeQ[#] && SquareFreeQ[#] && Divisible[#^2, Plus @@ (FactorInteger[#][[;;,1]]^2)] &]

%Y Cf. A131647.

%K nonn

%O 1,1

%A _Amiram Eldar_, Feb 21 2020