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 A072611 Numbers n such that phi(n) divides sigma(n+1)-sigma(n). 0
 1, 2, 6, 14, 30, 40, 70, 140, 170, 174, 206, 215, 238, 390, 459, 518, 923, 957, 1334, 1364, 1540, 1634, 2685, 2974, 4364, 5180, 5934, 6048, 6467, 6510, 6623, 8028, 8094, 8260, 8814, 12136, 12954, 14099, 14841, 15416, 16472, 17094, 17835, 17927, 18873 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 LINKS FORMULA Conjecture : lim n -> infinity Log(a(n))/Log(n) exists = 2, 6....... MATHEMATICA Select[Range[20000], Divisible[DivisorSigma[1, #+1]-DivisorSigma[1, #], EulerPhi[#]]&] (* Harvey P. Dale, Sep 15 2011 *) CROSSREFS Sequence in context: A063452 A009299 A330766 * A284023 A192966 A339668 Adjacent sequences:  A072608 A072609 A072610 * A072612 A072613 A072614 KEYWORD nonn AUTHOR Benoit Cloitre, Aug 07 2002 STATUS approved

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Last modified September 19 18:36 EDT 2021. Contains 347564 sequences. (Running on oeis4.)