Number of descent sequences of length n without two consecutive identical elements (descent sequences without flat steps).
A238425
Number of descent sequences of length n without two consecutive identical elements (descent sequences without flat steps).
Terms
- a(0) =1a(1) =1a(2) =1a(3) =1a(4) =2a(5) =4a(6) =11a(7) =34a(8) =124a(9) =512a(10) =2380a(11) =12294a(12) =69972a(13) =435399a(14) =2942672a(15) =21478882a(16) =168473955a(17) =1413823577a(18) =12644505883a(19) =120097766639
External references
- oeis: A238425