Number of permutations of length n with exactly two valleys.
A000487
Number of permutations of length n with exactly two valleys.
Terms
- a(0) =16a(1) =272a(2) =2880a(3) =24576a(4) =185856a(5) =1304832a(6) =8728576a(7) =56520704a(8) =357888000a(9) =2230947840a(10) =13754155008a(11) =84134068224a(12) =511780323328
External references
- oeis: A000487