Hermite numbers.

Terms

a(0) =1a(1) =0a(2) =-2a(3) =0a(4) =12a(5) =0a(6) =-120a(7) =0a(8) =1680a(9) =0a(10) =-30240a(11) =0a(12) =665280a(13) =0a(14) =-17297280a(15) =0a(16) =518918400a(17) =0a(18) =-17643225600a(19) =0a(20) =670442572800a(21) =0a(23) =0a(25) =0a(27) =0a(29) =0a(31) =0