Number of permutations of [n] with the property that no subsequence k(k+1)(k+2) or (k+2)(k+1)k occurs but k(k+1) or (k+1)k occurs.

A370485

Number of permutations of [n] with the property that no subsequence k(k+1)(k+2) or (k+2)(k+1)k occurs but k(k+1) or (k+1)k occurs.

Terms

    a(0) =0a(1) =0a(2) =2a(3) =4a(4) =16a(5) =78a(6) =480a(7) =3436a(8) =28050a(9) =256868a(10) =2607584a(11) =29061022a(12) =352747696a(13) =4632195548a(14) =65432845858a(15) =989341728564

External references