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

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

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 * A351568 A174544 A168423

Adjacent sequences: A091255 A091256 A091257 * A091259 A091260 A091261

Keyword

easy,nonn,frac

Author

Labos Elemer, Feb 12 2004

Status

approved