Number of linear arrangements of n blue, n red and n green items such that first and last elements have the same color but there are no adjacent items of the same color.
A110711
Number of linear arrangements of n blue, n red and n green items such that first and last elements have the same color but there are no adjacent items of the same color.
Terms
- a(0) =0a(1) =6a(2) =42a(3) =288a(4) =1992a(5) =13980a(6) =99432a(7) =715344a(8) =5196336a(9) =38056284a(10) =280658100a(11) =2082218160a(12) =15528409920a(13) =116331315360a(14) =874985339760
External references
- oeis: A110711