A145662 a(n) = numerator of polynomial of genus 1 and level n for m = 5 = A[1,n](5).

0, 5, 55, 835, 8365, 41837, 209195, 7321885, 73218955, 1098284605, 5491423277, 302028282755, 1510141416085, 98159192073245, 490795960391965, 2453979801983849, 24539798019883535, 2085882831690821195

Offset

1,2

Comments

For numerator of polynomial of genus 1 and level n for m = 1 see A001008

Definition: The polynomial A[1,2n+1](m) = A[genus 1,level n] is here defined as

Sum_{d=1..n-1} m^(n-d)/d.

Few first A[1,n](m):

n=1: A[1,1](m)= 0;

n=2: A[1,2](m)= m;

n=3: A[1,3](m)= m/2 + m^2;

n=4: A[1,4](m)= m/4 + m^2/3 + m^3/2 + m^4.

General formula which uses these polynomials is:

(1/(n+1))Hypergeometric2F1[1,n,n+1,1/m] = Sum_{x>=0} m^(-x)/(x+n) = m^n*arctanh((2m-1)/(2m^2-2m+1)) - A[1,n](m) = m^n*log(m/(m-1)) - A[1,n](m).

The sequence of denominators is ?, 1, 2, 6, 12, 12, 12, 84, ... - Matthew J. Samuel, Jan 30 2011

Links

Table of n, a(n) for n=1..18.

Maple

A145662 := proc(n) add( 5^(n-d)/d, d=1..n-1) ; numer(%) ; end proc: # R. J. Mathar, Feb 01 2011

Mathematica

m = 5; aa = {}; Do[k = 0; Do[k = k + m^(r - d)/d, {d, 1, r - 1}]; AppendTo[aa, Numerator[k]], {r, 1, 30}]; aa

Crossrefs

Cf. A145609-A145640, A145656, A145658, A145660, A145664, A145666.

Cf. A006245.

Sequence in context: A234508 A132865 A294051 * A362653 A094418 A365588

Adjacent sequences: A145659 A145660 A145661 * A145663 A145664 A145665

Keyword

frac,nonn

Author

Artur Jasinski, Oct 16 2008

Status

approved