A332738 Composite squarefree numbers k = Product_{i} p_i such that k^2 is divisible by Sum_{i} p_i^2.

5642, 9758, 15402, 51051, 72105, 73815, 113883, 134805, 149226, 202895, 270655, 352495, 443555, 552958, 627095, 650845, 831369, 831831, 841269, 870870, 881705, 956242, 1000110, 1088255, 1135290, 1255110, 1255215, 1418395, 1447095, 1455762, 1610070, 1718717, 1746955

Offset

1,1

Links

Amiram Eldar, Table of n, a(n) for n = 1..1000

Example

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

Mathematica

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

Crossrefs

Cf. A131647.

Sequence in context: A201252 A247402 A339961 * A359055 A184080 A234401

Adjacent sequences: A332735 A332736 A332737 * A332739 A332740 A332741

Keyword

nonn

Author

Amiram Eldar, Feb 21 2020

Status

approved