Begin with 2n cards in n piles of 2, the piles being {1,1},{2,2},{3,3},...,{n,n}. How many transpositions of adjacent (single) cards are needed to reverse the order of the piles?
A013927
Begin with 2n cards in n piles of 2, the piles being {1,1},{2,2},{3,3},...,{n,n}. How many transpositions of adjacent (single) cards are needed to reverse the order of the piles?
Terms
- a(0) =0a(1) =2a(2) =5a(3) =10a(4) =15a(5) =23a(6) =31a(7) =40
External references
- oeis: A013927