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A145612 Denominator of the polynomial A_l(x) = Sum_{d=1..l-1} x^(l-d)/d for index l=2n+1 evaluated at x=2. 2
1, 6, 15, 420, 63, 1386, 9009, 360360, 1531530, 29099070, 14549535, 1338557220, 1673196525, 10039179150, 145568097675, 72201776446800, 18050444111700, 9025222055850, 166966608033225, 667866432132900, 6845630929362225 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

For numerators see A145611. For general properties of A_l(x) see A145609.

LINKS

Table of n, a(n) for n=1..21.

MAPLE

A := proc(l, x) add(x^(l-d)/d, d=1..l-1) ; end: A145612 := proc(n) denom( A(2*n+1, 2)) ; end: seq(A145612(n), n=1..20) ; # R. J. Mathar, Aug 21 2009

MATHEMATICA

m = 2; 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: A235230 A024081 A145558 * A307812 A280964 A191463

Adjacent sequences:  A145609 A145610 A145611 * A145613 A145614 A145615

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 September 21 07:08 EDT 2019. Contains 327253 sequences. (Running on oeis4.)