Number of n X 2 0..2 arrays with every 1 immediately preceded by 0 to the left or above, and every 2 immediately preceded by both a 1 and a 0.
A203365
Number of n X 2 0..2 arrays with every 1 immediately preceded by 0 to the left or above, and every 2 immediately preceded by both a 1 and a 0.
Terms
- a(0) =2a(1) =9a(2) =30a(3) =110a(4) =390a(5) =1399a(6) =4998a(7) =17881a(8) =63940a(9) =228680a(10) =817820a(11) =2924801a(12) =10460002a(13) =37408329a(14) =133784090a(15) =478454630a(16) =1711106370a(17) =6119462399a(18) =21885149998a(19) =78268279361a(20) =279912339880
External references
- oeis: A203365