Number of complete mappings f(x) of Z_{2n+1} such that -(-id+f)^(-1)=f.

Terms

a(0) =1a(1) =1a(2) =0a(3) =4a(4) =0a(5) =0a(6) =80a(7) =48a(8) =0a(9) =3328a(10) =1920a(11) =0a(12) =270080a(13) =131328a(14) =0a(15) =3257736a(16) =16379904a(17) =0a(18) =5750476800a(19) =2942582784a(20) =0a(22) =706948005888a(23) =0