Erroneous version of A003781.

Terms

a(0) =1a(1) =0a(2) =0a(3) =56a(4) =14a(5) =0a(6) =0a(7) =576a(8) =84a(9) =0a(10) =0a(11) =1512a(12) =280a(13) =0a(14) =0a(15) =4032a(16) =574a(17) =0a(18) =0a(19) =5544a(20) =840a(21) =0a(22) =0