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 A088840 Denominator of sigma(4n)/sigma(n). 4
 1, 1, 1, 7, 1, 1, 1, 5, 1, 1, 1, 7, 1, 1, 1, 31, 1, 1, 1, 7, 1, 1, 1, 5, 1, 1, 1, 7, 1, 1, 1, 21, 1, 1, 1, 7, 1, 1, 1, 5, 1, 1, 1, 7, 1, 1, 1, 31, 1, 1, 1, 7, 1, 1, 1, 5, 1, 1, 1, 7, 1, 1, 1, 127, 1, 1, 1, 7, 1, 1, 1, 5, 1, 1, 1, 7, 1, 1, 1, 31, 1, 1, 1, 7, 1, 1, 1, 5, 1, 1, 1, 7, 1, 1, 1, 21, 1, 1, 1, 7, 1, 1 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,4 LINKS Antti Karttunen, Table of n, a(n) for n = 1..16384 MATHEMATICA Table[Numerator[DivisorSigma[1, 4*n]/DivisorSigma[1, n]], {n, 1, 128}] PROG (PARI) A088840(n) = denominator(sigma(4*n)/sigma(n)); \\ Antti Karttunen, Nov 18 2017 CROSSREFS See A088839 for numerator. Cf. A088837, A088838, A088841, A038712, A080278, A000203. Sequence in context: A174544 A168423 A072101 * A271498 A317940 A318674 Adjacent sequences:  A088837 A088838 A088839 * A088841 A088842 A088843 KEYWORD easy,nonn,mult,frac AUTHOR Labos Elemer, Nov 04 2003 EXTENSIONS Typo in definition corrected by Antti Karttunen, Nov 18 2017 STATUS approved

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Last modified July 23 11:44 EDT 2019. Contains 325254 sequences. (Running on oeis4.)