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A145664 a(n) = numerator of polynomial of genus 1 and level n for m = 6 = A[1,n](6). 4

%I #12 Jan 21 2019 04:18:57

%S 0,6,39,236,2835,42531,255191,10718052,257233353,2315100317,

%T 2315100338,152796622518,1833559470601,71508819355749,429052916136639,

%U 2574317496821836,123567239847463143,6301929232220740413

%N a(n) = numerator of polynomial of genus 1 and level n for m = 6 = A[1,n](6).

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

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

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

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

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

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

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

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

%C General formula which uses these polynomials is:

%C (1/(n+1))Hypergeometric2F1[1,n,n+1,1/m] =

%C Sum_{x>=0} m^(-x)/(x+n) =

%C m^n*arctanh((2m-1)/(2m^2-2m+1)) - A[1,n](m) =

%C m^n*log(m/(m-1)) - A[1,n](m).

%p A145664 := proc(n) add( 6^(n-d)/d,d=1..n-1) ; numer(%) ; end proc:

%p seq(A145664(n),n=1..20) ; # _R. J. Mathar_, Feb 01 2011

%t m = 6; aa = {}; Do[k = 0; Do[k = k + m^(r - d)/d, {d, 1, r - 1}]; AppendTo[aa, Numerator[k]], {r, 1, 30}]; aa

%Y Cf. A145609-A145640, A145656, A145658, A145660, A145662, A145664.

%K frac,nonn

%O 1,2

%A _Artur Jasinski_, Oct 16 2008

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