Auxiliary sequence for calculation of number of even permutations of degree n and order exactly 2.

A051684

Auxiliary sequence for calculation of number of even permutations of degree n and order exactly 2.

Terms

    a(0) =0a(1) =-1a(2) =-3a(3) =-3a(4) =5a(5) =15a(6) =-21a(7) =-133a(8) =27a(9) =1215a(10) =935a(11) =-12441a(12) =-23673a(13) =138047a(14) =469455a(15) =-1601265a(16) =-9112561a(17) =18108927a(18) =182135007a(19) =-161934625a(20) =-3804634785a(21) =-404007681a(22) =83297957567

External references