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 A091258 Denominator of sigma(3,n)/sigma(1,n). 4

%I

%S 1,1,1,7,1,1,1,1,13,1,1,1,1,1,1,1,1,13,1,1,1,1,1,1,31,1,1,7,1,1,1,7,1,

%T 1,1,91,1,1,1,1,1,1,1,7,13,1,1,1,19,31,1,7,1,1,1,1,1,1,1,1,1,1,13,1,1,

%U 1,1,1,1,1,1,1,1,1,31,1,1,1,1,1,1,1,1,1,1,1,1,1,1,13,1,7,1,1,1,1,1,19,13

%N Denominator of sigma(3,n)/sigma(1,n).

%H Antti Karttunen, <a href="/A091258/b091258.txt">Table of n, a(n) for n = 1..65537</a>

%t Denominator[Table[DivisorSigma[3,n]/DivisorSigma[1,n],{n,100}]] (* _Harvey P. Dale_, Oct 06 2017 *)

%o (PARI) a(n) = denominator(sigma(n, 3)/sigma(n)); \\ _Michel Marcus_, Dec 29 2013

%Y Cf. A001158, A000203, A091259-A091261.

%K easy,nonn,frac

%O 1,4

%A _Labos Elemer_, Feb 12 2004

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Last modified September 23 02:41 EDT 2021. Contains 347609 sequences. (Running on oeis4.)