Number of involutions (plus identity) in a fixed Sylow 2-subgroup of the symmetric group of degree 2n.

A332868

Number of involutions (plus identity) in a fixed Sylow 2-subgroup of the symmetric group of degree 2n.

Terms

    a(0) =1a(1) =2a(2) =6a(3) =12a(4) =44a(5) =88a(6) =264a(7) =528a(8) =2064a(9) =4128a(10) =12384a(11) =24768a(12) =90816a(13) =181632a(14) =544896a(15) =1089792a(16) =4292864a(17) =8585728a(18) =25757184a(19) =51514368a(20) =188886016a(21) =377772032a(22) =1133316096a(23) =2266632192a(24) =8860471296a(25) =17720942592a(26) =53162827776a(27) =106325655552a(28) =389860737024a(29) =779721474048

External references