A035047 Denominators of alternating sum transform (PSumSIGN) of Harmonic numbers H(n) = A001008/A002805.

1, 2, 3, 4, 15, 12, 105, 24, 315, 120, 3465, 40, 45045, 280, 45045, 560, 765765, 5040, 14549535, 5040, 14549535, 55440, 334639305, 55440, 1673196525, 720720, 5019589575, 720720, 145568097675, 720720

Offset

1,2

Links

Robert Israel, Table of n, a(n) for n = 1..2000

N. J. A. Sloane, Transforms

Formula

G.f. for A035048(n)/A035047(n) : log(1-x)/(x^2-1). - Benoit Cloitre, Jun 15 2003

a(n) = denominator((-1)^(n+1)*1/2*(log(2)+(-1)^(n+1)*(gamma+1/2*(psi(1+n/2)-psi(3/2+n/2))+psi(2+n)))), with gamma the Euler-Mascheroni constant. - [Gerry Martens, Apr 28 2011]

Maple

S:= series(log(1-x)/(x^2-1), x, 101):
seq(denom(coeff(S, x, j)), j=1..100); # Robert Israel, Jun 02 2015

Prog

(PARI) a(n)=denominator(polcoeff(log(1-x)/(x^2-1)+O(x^(n+1)), n))

Crossrefs

Cf. A035048.

Sequence in context: A367742 A251637 A365436 * A347335 A348672 A334619

Adjacent sequences: A035044 A035045 A035046 * A035048 A035049 A035050

Keyword

nonn,frac,easy

Author

N. J. A. Sloane.

Status

approved