Number of permutations of 1..n avoiding adjacent step pattern up, up, down, down.
A177522
Number of permutations of 1..n avoiding adjacent step pattern up, up, down, down.
Terms
- a(0) =1a(1) =1a(2) =2a(3) =6a(4) =24a(5) =114a(6) =648a(7) =4284a(8) =32256a(9) =273616a(10) =2578352a(11) =26725776a(12) =302273664a(13) =3703441104a(14) =48865510848a(15) =690823736064
External references
- oeis: A177522