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

Author

Emeric Deutsch, Mar 12 2005

Keywords

• frac
• nonn

Examples

			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.
		

Links

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

Crossrefs

Cf. A104528.

Programs

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 *)