A128600 a(n) = the denominator of the continued fraction [[n/1];[n/2],[n/3],..,[n/n]], where [x] is floor(x).

1, 1, 2, 5, 8, 27, 44, 137, 305, 905, 1466, 7411, 11986, 33597, 91007, 322205, 521306, 2292156, 3708875, 15639101, 40100349, 106348943, 172076807, 1071988711, 2129108426, 5564227811, 13812311521, 53326260495, 86283685147, 492560346093

Offset

1,3

Links

Table of n, a(n) for n=1..30.

Maple

A128600 := proc(n) local a, i ; a := 1 ; for i from n-1 to 1 by -1 do a := floor(n/i)+1/a ; od ; RETURN(denom(a)) ; end: for n from 1 to 40 do printf("%d, ", A128600(n)) ; od ; # R. J. Mathar, Jun 06 2007

Mathematica

Table[Denominator[FromContinuedFraction[Table[Floor[n/i], {i, 1, n}]]], {n, 1, 30}] (* Stefan Steinerberger, Jun 02 2007 *)

Crossrefs

Cf. A128599, A128601.

Sequence in context: A192476 A093365 A209865 * A078993 A066846 A304043

Adjacent sequences: A128597 A128598 A128599 * A128601 A128602 A128603

Keyword

frac,nonn

Author

Leroy Quet, Mar 12 2007

Extensions

More terms from Stefan Steinerberger and R. J. Mathar, Jun 02 2007

Status

approved