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

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

Offset

0,3

Comments

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

Links

Table of n, a(n) for n=0..8.

Formula

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

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 *)

Crossrefs

Cf. A027611.

Sequence in context: A132513 A034174 A231831 * A112404 A189216 A291213

Adjacent sequences: A119523 A119524 A119525 * A119527 A119528 A119529

Keyword

frac,nonn

Author

Alexander Adamchuk, Jul 27 2006

Status

approved