Number of permutations of [n] avoiding the pattern 12-34.
A113226
Number of permutations of [n] avoiding the pattern 12-34.
Terms
- a(0) =1a(1) =1a(2) =2a(3) =6a(4) =23a(5) =107a(6) =585a(7) =3669a(8) =25932a(9) =203768a(10) =1761109a(11) =16595757a(12) =169287873a(13) =1857903529a(14) =21823488238a(15) =273130320026
External references
- oeis: A113226