The number of partitions of the set [n] where each element can be colored 1 or 2 avoiding the patterns 1^11^1 and 1^22^1 in the pattern sense.
A208275
The number of partitions of the set [n] where each element can be colored 1 or 2 avoiding the patterns 1^11^1 and 1^22^1 in the pattern sense.
Terms
- a(0) =2a(1) =5a(2) =10a(3) =21a(4) =46a(5) =107a(6) =262a(7) =675a(8) =1818a(9) =5105a(10) =14882a(11) =44929a(12) =140070a(13) =450055a(14) =1487294a(15) =5047327a(16) =17562546a(17) =62578845a(18) =228062522a(19) =849213293a(20) =3227667742a(21) =12511072803a(22) =49417391350a(23) =198758992859a(24) =813460577482
External references
- oeis: A208275