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A069265
Numbers k such that Sum_{d|k} d/core(d) > k, where core(d) is the squarefree part of d.
1
4, 8, 9, 16, 18, 25, 32, 36, 48, 49, 50, 64, 72, 81, 98, 100, 108, 121, 128, 144, 162, 169, 192, 196, 200, 225, 242, 256, 288, 289, 300, 324, 338, 361, 392, 400, 432, 441, 450, 484, 512, 529, 576, 578, 588, 625, 648, 676, 722, 729, 768, 784, 800, 841, 882, 900
OFFSET
1,1
LINKS
FORMULA
k such that A068976(k) > k.
MATHEMATICA
f[p_, e_] := If[OddQ[e], 2*(p^(e + 1) - 1)/(p^2 - 1), (p^(e + 2) + p^e - 2)/(p^2 - 1)]; Select[Range[2, 1000], Times @@ (f @@@ FactorInteger[#]) > # &] (* Amiram Eldar, Sep 03 2020 *)
CROSSREFS
Sequence in context: A166402 A255586 A034038 * A336359 A371013 A359680
KEYWORD
easy,nonn
AUTHOR
Benoit Cloitre, Apr 14 2002
STATUS
approved