Exponential generating function is tanh(log(1+x)).

Terms

a(0) =0a(1) =1a(2) =-1a(3) =0a(4) =6a(5) =-30a(6) =90a(7) =0a(8) =-2520a(9) =22680a(10) =-113400a(11) =0a(12) =7484400a(13) =-97297200a(14) =681080400a(15) =0a(16) =-81729648000a(19) =0a(23) =0