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%I #33 Feb 26 2014 14:44:40
%S -1,1,-1,1,-5,63,-315,99,-675675,135135,-1640925,83329155,-4583103525,
%T 5791834125,-71152682225625,14230536445125,-26797763435625,
%U 24833960277501375,-73881031825566590625,8546099690638125,-106610328924292590271875
%N A129779(n+2)/A006954(n).
%C In A129779 or A097801 there is no mention of a link with the Bernoulli numbers.
%C It appears that a(n+6) is divisible by 4*(n+4)^2-1 and that the sum of the digits of a(n+5) is a multiple of 9.
%H Vincenzo Librandi, <a href="/A238087/b238087.txt">Table of n, a(n) for n = 0..200</a>
%F a(n+2) = -A004193(n+1)/A000367(n+1).
%e a(0) = -1/1, a(1) = 2/2, a(2) = -6/6, a(3) = 30/30, a(4) = -210/42 =-5.
%t a[0] = -1; a[1] = 1; a[n_] := (-1)^(n+1)*(2*n)!/(2^(n-1)*n!*Denominator[BernoulliB[2*n-2]]); Table[a[n], {n, 0, 20}] (* _Jean-François Alcover_, Feb 24 2014 *)
%Y Cf. A000466.
%K sign
%O 0,5
%A _Paul Curtz_, Feb 24 2014
%E More terms from _Jean-François Alcover_, Feb 24 2014
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