Number of permutations of 1..n avoiding adjacent step pattern up, down, down.

A177479

Number of permutations of 1..n avoiding adjacent step pattern up, down, down.

Terms

    a(0) =1a(1) =1a(2) =2a(3) =6a(4) =21a(5) =90a(6) =450a(7) =2619a(8) =17334a(9) =129114a(10) =1067661a(11) =9713682a(12) =96393726a(13) =1036348587a(14) =11998603710a(15) =148842430470

External references