A104529 Denominator of Sum_{k=1..n} 1/tau(k), where tau(k) is the number of divisors function.

1, 2, 1, 3, 6, 12, 12, 6, 6, 12, 12, 12, 12, 6, 12, 60, 60, 20, 20, 60, 15, 60, 60, 120, 40, 40, 40, 120, 120, 30, 15, 30, 60, 15, 60, 180, 180, 45, 180, 360, 360, 45, 90, 45, 90, 180, 180, 180, 180, 180, 90, 45, 90, 360, 360, 45, 180, 90, 45, 180, 180, 90, 45, 315, 1260

Offset

1,2

Links

Harvey P. Dale, Table of n, a(n) for n = 1..1000

Example

1,3/2,2,7/3,17/6
a(4)=3 because 1/tau(1)+1/tau(2)+1/tau(3)+1/tau(4)=1/1+1/2+1/2+1/3=7/3.

Maple

with(numtheory): a:=n->denom(sum(1/tau(k), k=1..n)): seq(a(n), n=1..70);

Mathematica

Denominator[Accumulate[1/#&/@DivisorSigma[0, Range[70]]]] (* Harvey P. Dale, Dec 18 2012 *)

Crossrefs

Cf. A104528.

Sequence in context: A025110 A075346 A357844 * A095024 A049900 A024741

Adjacent sequences: A104526 A104527 A104528 * A104530 A104531 A104532

Keyword

frac,nonn

Author

Emeric Deutsch, Mar 12 2005

Status

approved