Number of permutations of size n which are both two-clumped and co-two-clumped.

A375923

Number of permutations of size n which are both two-clumped and co-two-clumped.

Terms

    a(0) =1a(1) =1a(2) =2a(3) =6a(4) =24a(5) =112a(6) =582a(7) =3272a(8) =19550a(9) =122628a(10) =800392a(11) =5400342a(12) =37475474a(13) =266412680a(14) =1934033968a(15) =14300538652a(16) =107471798112a(17) =819442325086

External references