Number of paths from (0,0) to (n,n) that use E(1,0) and N(0,1) as steps and have even number of East steps below the line y=x-1.
A268213
Number of paths from (0,0) to (n,n) that use E(1,0) and N(0,1) as steps and have even number of East steps below the line y=x-1.
Terms
- a(0) =1a(1) =2a(2) =5a(3) =16a(4) =51a(5) =180a(6) =622a(7) =2288a(8) =8227a(9) =30940a(10) =113882a(11) =434112a(12) =1622414a(13) =6240360a(14) =23572668a(15) =91245600a(16) =347398435a(17) =1351035180a(18) =5174839714a(19) =20197293600a(20) =77729205658a(21) =304232711640
External references
- oeis: A268213