1,3

This is very similar to A128438, which is a different sequence. They differ at n=6 (and nowhere else?). - N. J. A. Sloane (njas(AT)research.att.com), Nov 21 2008

Denominator of 1/n + 2/(n-1) + 3/(n-2) + ... + (n-1)/2 + n.

Denominator of sum(k=1,n,frac(n/k)) where frac(x/y) denotes the fractional part of x/y. - Benoit Cloitre (benoit7848c(AT)orange.fr), Oct 03 2002

Denominator of Sum{n/d : 1<d<n and n mod d > 0}. Numerator = A079076. - Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), Dec 21 2002

a(n) is odd iff n is a power of 2. - Benoit Cloitre (benoit7848c(AT)orange.fr), Oct 03 2002

Eric Weisstein's World of Mathematics, Complete Set

Denominators of coefficients in expansion of -ln(1-x)/(1-x)^2. Denominators of (n+1)*(harmonic(n+1)-1). Denominators of (n+1)*(Psi(n+2)+gamma-1). - Vladeta Jovovic (vladeta(AT)eunet.rs), Sep 02 2002

ZL:=n->sum(sum(1/i, i=1..n), j=1..n): a:=n->floor(denom(ZL(n))): seq(a(n), n=1..30); - Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), Jun 14 2007

Harmonic numbers = A001008/A002805. Cf. A001705, A006675, A027612, A049820, A024816.

Cf. A128438.

Sequence in context: A081526 A075711 A079077 this_sequence A068550 A093432 A100561

Adjacent sequences: A027608 A027609 A027610 this_sequence A027612 A027613 A027614

nonn,easy,frac

Glen Burch (gburch(AT)erols.com)

Entry revised by N. J. A. Sloane (njas(AT)research.att.com) following a suggestion of Eric Weisstein, Jul 02 2004.