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A091258 Denominator of sigma(3,n)/sigma(1,n). 4
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, 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, 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 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,4

LINKS

Antti Karttunen, Table of n, a(n) for n = 1..65537

MATHEMATICA

Denominator[Table[DivisorSigma[3, n]/DivisorSigma[1, n], {n, 100}]] (* Harvey P. Dale, Oct 06 2017 *)

PROG

(PARI) a(n) = denominator(sigma(n, 3)/sigma(n)); \\ Michel Marcus, Dec 29 2013

CROSSREFS

Cf. A001158, A000203, A091259-A091261.

Sequence in context: A331927 A285483 A284097 * A174544 A168423 A336844

Adjacent sequences:  A091255 A091256 A091257 * A091259 A091260 A091261

KEYWORD

easy,nonn,frac

AUTHOR

Labos Elemer, Feb 12 2004

STATUS

approved

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Last modified July 25 03:36 EDT 2021. Contains 346282 sequences. (Running on oeis4.)