A094147 Numbers that can be written as sum of squares of two divisors.

2, 8, 18, 20, 32, 50, 72, 80, 90, 98, 128, 162, 180, 200, 242, 272, 288, 320, 338, 360, 392, 450, 468, 500, 512, 578, 648, 650, 720, 722, 800, 810, 882, 968, 980, 1058, 1088, 1152, 1250, 1280, 1332, 1352, 1440, 1458, 1568, 1620, 1682, 1800, 1872

Offset

1,1

Links

Amiram Eldar, Table of n, a(n) for n = 1..10000

Example

6 and 12 are divisors of 180 and 6^2 + 12^2 = 36 + 144 = 180, therefore 180 is a term.

Mathematica

aQ[n_] := AnyTrue[n - Divisors[n]^2, IntegerQ[(s = Sqrt[#])] && s>0 && Divisible[n, s] &]; Select[Range[2, 1872], aQ] (* Amiram Eldar, Sep 02 2019 *)

Crossrefs

Subsequence of A000404.

A001105 is a subsequence.

Sequence in context: A228615 A267823 A063664 * A117612 A320662 A171613

Adjacent sequences: A094144 A094145 A094146 * A094148 A094149 A094150

Keyword

nonn

Author

Reinhard Zumkeller, Jun 01 2004

Status

approved