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A220448
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Define a sequence u(n) by u(1)=1; thereafter u(n) = f(n)/f(n-1) where f(n) = (-1)^(n+1)*A105750(n); sequence gives numerator(u(n)).
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3
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1, 1, -10, -1, 19, -73, 662, -2795, 281, -4511, 21746, -322921, 1035215, -720817, 1077518, -87995911, -34376687, 929280875, -92673902, 6986985769, -33833494045, 243540693677, -1817775985570, 13097400661955, -27199287430171, 8249498995171439, -112427012362483262, 3008079144099400625, -10365435567354511181
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OFFSET
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1,3
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COMMENTS
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Also u(n) = n*x(n-1)-1, where x(n) is defined in A220447.
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LINKS
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EXAMPLE
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The sequence u(n) begins 1, 1, -10, -1, 19, -73/19, 662/73, -2795/331, 281/43, -4511/281, 21746/4511, ...
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MAPLE
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if n= 1 then
1 ;
else
numer(%) ;
end if;
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MATHEMATICA
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x[n_] := x[n] = If[n == 1, 1, (x[n-1] + n)/(1 - n*x[n-1])];
u[n_] := If[n == 1, 1, n*x[n-1] - 1];
a[n_] := Numerator[u[n]];
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CROSSREFS
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KEYWORD
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sign,frac
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AUTHOR
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STATUS
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approved
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