Number of permutations on n letters that have only cycles of length 3 or less.
A057693
Number of permutations on n letters that have only cycles of length 3 or less.
Terms
- a(0) =1a(1) =1a(2) =2a(3) =6a(4) =18a(5) =66a(6) =276a(7) =1212a(8) =5916a(9) =31068a(10) =171576a(11) =1014696a(12) =6319512a(13) =41143896a(14) =281590128a(15) =2007755856a(16) =14871825936a(17) =114577550352a(18) =913508184096
External references
- oeis: A057693