A173494 Numbers m such that no square greater than 1 can be written as sum of distinct divisors of m.
1, 2, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 38, 41, 43, 47, 53, 58, 59, 61, 65, 67, 71, 73, 74, 77, 79, 82, 83, 85, 86, 89, 91, 97, 101, 103, 106, 107, 109, 113, 127, 131, 133, 134, 137, 139, 145, 146, 149, 151, 157, 163, 167, 173, 178, 179, 181, 185, 187, 191, 193, 197
Offset: 1
Keywords
Links
- Amiram Eldar, Table of n, a(n) for n = 1..10000
Programs
-
Mathematica
q[m_] := Module[{d = Divisors[m], sum, sq, x}, sum = Plus @@ d; sq = Range[2, Floor[Sqrt[sum]]]^2; Total[CoefficientList[Product[1 + x^i, {i, d}], x][[1 + sq]]] == 0]; Select[Range[200], q] (* Amiram Eldar, Apr 16 2025 *)
Formula
A173493(a(n)) = 1.
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