A119526 Odd denominators of n * n-th harmonic number = A027611[2^n].

1, 1, 3, 35, 45045, 4512611027925, 2052546673789621992207225, 104326219460917277964091790659689347988584942875383375, 65134729714436885436168002936626505274493455112928327538888490982573786624726691153873697518277375333357875

Offset: 0

Author

Alexander Adamchuk, Jul 27 2006

Keywords

• frac
• nonn

Comments

The next term (a(9)) has 218 digits. - Harvey P. Dale, Sep 12 2016

Crossrefs

Cf. A027611.

Programs

Mathematica

Denominator[Table[2^n*Sum[1/k,{k,1,2^n}],{n,0,10}]]
With[{nn=300},Select[Denominator[Times@@@Thread[{Range[nn],HarmonicNumber[Range[nn]]}]],OddQ]] (* Harvey P. Dale, Sep 12 2016 *)

Formula

a(n) = Denominator[2^n*Sum[1/k,{k,1,2^n}]]. a(n) = A027611[2^n].