The number of partitions of the set [n] where each element can be colored 1 or 2 avoiding the patterns 1^11^2, 1^12^2, and 1^22^1 in the pattern sense.
A209798
The number of partitions of the set [n] where each element can be colored 1 or 2 avoiding the patterns 1^11^2, 1^12^2, and 1^22^1 in the pattern sense.
Terms
- a(0) =2a(1) =5a(2) =12a(3) =33a(4) =108a(5) =411a(6) =1760a(7) =8287a(8) =42302a(9) =231959a(10) =1357150a(11) =8427205a(12) =55288886a(13) =381798657a(14) =2765917104a(15) =20960284309a(16) =165729739624
External references
- oeis: A209798