

A170920


Write x*cot(x) = Product_{n>=1} (1 + g_n*x^(2*n)); a(n) = numerator(g_n).


1



1, 1, 1, 16, 91, 58844, 73267, 1196588, 49830764, 1715330699, 35249288479, 374085503198546, 732125336837021, 779432268293710651, 30015706187367326893, 183998031852529374082, 46789354983174555461, 115977125342651266593554, 248130101882943187003954597, 13171311382437535379302071714878
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OFFSET

1,4


LINKS

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


EXAMPLE

1/3, 1/45, 1/105, 16/4725, 91/66825, 58844/127702575, 73267/383107725, ...


MAPLE

t1:=x*cot(x);
L:=100;
t0:=series(t1, x, L);
g:=[];
M:=20; # number of terms to get
t2:=t0:
for n from 1 to M do
t3:=coeff(t2, x, 2*n); t2:=series(t2/(1+t3*x^(2*n)), x, L); g:=[op(g), t3];
od:
g;
g1:=map(numer, g);
g2:=map(denom, g);


CROSSREFS

Cf. A170921, A170908A170919.
Sequence in context: A050406 A047674 A153029 * A027938 A301527 A185458
Adjacent sequences: A170917 A170918 A170919 * A170921 A170922 A170923


KEYWORD

sign,frac


AUTHOR

N. J. A. Sloane, Jan 31 2010


EXTENSIONS

Corrected definition and terms  N. J. A. Sloane, Oct 04 2019 (thanks to Petros Hadjicostas for pointing out that something was wrong).


STATUS

approved



