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A091260
Denominator of sigma_3(n)/sigma_2(n).
5
1, 5, 5, 21, 13, 25, 25, 17, 91, 65, 61, 15, 85, 125, 65, 11, 145, 455, 181, 13, 125, 305, 265, 85, 651, 425, 41, 525, 421, 325, 481, 455, 305, 725, 325, 1911, 685, 181, 425, 17, 841, 625, 925, 427, 169, 1325, 1105, 55, 817, 1085, 725, 255, 1405, 205, 793, 425, 181
OFFSET
1,2
COMMENTS
If n is an odd prime then a(n) = A001844((n-1)/2). - Robert Israel, Jan 26 2018
LINKS
MAPLE
seq(denom(numtheory:-sigma[3](n)/numtheory:-sigma[2](n)), n=1..100); # Robert Israel, Jan 26 2018
MATHEMATICA
Denominator[Table[DivisorSigma[3, n]/DivisorSigma[2, n], {n, 60}]] (* Harvey P. Dale, Nov 03 2011 *)
PROG
(PARI) a(n) = my(f = factor(n)); denominator(sigma(f, 3)/sigma(f, 2)); \\ Amiram Eldar, Dec 20 2024
CROSSREFS
KEYWORD
easy,nonn,frac
AUTHOR
Labos Elemer, Feb 12 2004
STATUS
approved