A225354 Numbers that can be written as sum of distinct squarefree divisors.

1, 2, 3, 5, 6, 7, 10, 11, 12, 13, 14, 15, 17, 19, 21, 22, 23, 26, 29, 30, 31, 33, 34, 35, 37, 38, 39, 41, 42, 43, 46, 47, 51, 53, 55, 57, 58, 59, 60, 61, 62, 65, 66, 67, 69, 70, 71, 73, 74, 77, 78, 79, 82, 83, 84, 85, 86, 87, 89, 91, 93, 94, 95, 97, 101, 102

Offset: 1

Author

Reinhard Zumkeller, May 05 2013

Keywords

• nonn

Comments

A225245(a(n)) > 0.

Links

• Reinhard Zumkeller, Table of n, a(n) for n = 1..1000

Crossrefs

Cf. A225353 (complement).

Programs

Haskell

import Data.List (findIndices)
a225354 n = a225354_list !! (n-1)
a225354_list = map (+ 1) $ findIndices (> 0) a225245_list

Mathematica

f[n_] := f[n] = Coefficient[Product[If[MoebiusMu[d] != 0, 1 + x^d, 1], {d, Divisors[n]}], x, n];
ParallelTable[If[f[k] > 0, k, Nothing], {k, 1, 1000}] (* Jean-François Alcover, May 04 2024, after Ilya Gutkovskiy in A225245 *)