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Triangle of the denominators of the coefficients [x^k] P(n,x) defined in A141904.
4

%I #8 Oct 02 2012 11:35:26

%S 1,3,1,5,3,1,7,45,1,1,9,105,15,3,1,11,1575,945,15,3,1,13,10395,175,

%T 945,9,1,1,15,315315,17325,14175,189,15,3,1,17,45045,23648625,7425,

%U 2835,189,15,3,1,19,6891885,1576575,23648625,93555,945,135,45,1,1,21,72747675,7309575

%N Triangle of the denominators of the coefficients [x^k] P(n,x) defined in A141904.

%C Are all the denominators odd?

%t ClearAll[u, p]; u[n_] := (-1)^n/(2*n + 1); p[0][x_] := u[0]; p[n_][x_] := p[n][x] = u[n] + x*Sum[u[i]*p[n - i - 1][x] , {i, 0, n-1}] // Expand; row[n_] := CoefficientList[ p[n][x], x]; Table[row[n], {n, 0, 10}] // Flatten // Denominator (* _Jean-François Alcover_, Oct 02 2012 *)

%Y Cf. A141904 (numerators).

%K nonn,frac,tabl

%O 0,2

%A _Paul Curtz_, Sep 14 2008

%E Edited and extended by _R. J. Mathar_, Aug 24 2009