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A225354
Numbers that can be written as sum of distinct squarefree divisors.
5
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
1,2
COMMENTS
A225245(a(n)) > 0.
LINKS
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 *)
PROG
(Haskell)
import Data.List (findIndices)
a225354 n = a225354_list !! (n-1)
a225354_list = map (+ 1) $ findIndices (> 0) a225245_list
CROSSREFS
Cf. A225353 (complement).
Sequence in context: A349810 A317092 A349019 * A166111 A004762 A061854
KEYWORD
nonn
AUTHOR
Reinhard Zumkeller, May 05 2013
STATUS
approved