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A145610 Denominator of the polynomial A_l(x) = Sum_{d=1..l-1} x^(l-d)/d for index l=2n+1 evaluated at x=1. 2
2, 12, 20, 280, 2520, 27720, 360360, 720720, 4084080, 15519504, 5173168, 356948592, 8923714800, 80313433200, 2329089562800, 144403552893600, 13127595717600, 13127595717600, 485721041551200, 485721041551200 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

For numerators and explicit examples of the polynomials see A145609.

LINKS

Table of n, a(n) for n=1..20.

MAPLE

A := proc(l, x) add(x^(l-d)/d, d=1..l-1) ; end: A145610 := proc(n) denom( A(2*n+1, 1)) ; end: seq(A145610(n), n=1..20) ; # R. J. Mathar, Aug 21 2009

MATHEMATICA

m = 1; aa = {}; Do[k = 0; Do[k = k + m^(2 r + 1 - d)/d, {d, 1, 2 r}]; AppendTo[aa, Denominator[k]], {r, 1, 30}]; aa (* Artur Jasinski *)

CROSSREFS

Cf. A145609 - A145640.

Sequence in context: A174478 A331947 A145634 * A185399 A096108 A098941

Adjacent sequences:  A145607 A145608 A145609 * A145611 A145612 A145613

KEYWORD

frac,nonn

AUTHOR

Artur Jasinski, Oct 14 2008

EXTENSIONS

Edited by R. J. Mathar, Aug 21 2009

STATUS

approved

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Last modified May 14 13:20 EDT 2021. Contains 343884 sequences. (Running on oeis4.)