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 A158298 Denominators of averages of squares of the divisors of n. 3
 1, 2, 1, 1, 1, 2, 1, 4, 3, 2, 1, 1, 1, 2, 1, 5, 1, 6, 1, 1, 1, 2, 1, 4, 1, 2, 1, 1, 1, 2, 1, 2, 1, 2, 1, 3, 1, 2, 1, 4, 1, 2, 1, 1, 3, 2, 1, 1, 1, 2, 1, 1, 1, 2, 1, 4, 1, 2, 1, 1, 1, 2, 3, 7, 1, 2, 1, 1, 1, 2, 1, 12, 1, 2, 1, 1, 1, 2, 1, 5, 5, 2, 1, 1, 1, 2 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS Average of squares of the divisors of n = A001157(n)/A000005(n). Iff a(n) = 1, n is in A020486. LINKS Amiram Eldar, Table of n, a(n) for n = 1..10000 MATHEMATICA Array[Denominator[DivisorSigma[2, #]/DivisorSigma[0, #]] &, 100] (* Amiram Eldar, Jul 15 2019 *) PROG (PARI) a(n) = denominator(sigma(n, 2)/numdiv(n)) \\ Michel Marcus, Jun 13 2013 CROSSREFS Cf. A001157, A000005, A020486, A158299 (for numerators). Sequence in context: A051119 A159269 A186728 * A009191 A229969 A260909 Adjacent sequences:  A158295 A158296 A158297 * A158299 A158300 A158301 KEYWORD nonn,frac AUTHOR Jaroslav Krizek, Mar 15 2009 EXTENSIONS Data corrected and extended by Amiram Eldar, Jul 15 2019 STATUS approved

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Last modified May 12 04:27 EDT 2021. Contains 343810 sequences. (Running on oeis4.)