Number of walks within N^2 (the first quadrant of Z^2) starting and ending at (0,0) and consisting of n steps taken from {(-1, -1), (-1, 0), (0, 1), (1, 0)}.
A151352
Number of walks within N^2 (the first quadrant of Z^2) starting and ending at (0,0) and consisting of n steps taken from {(-1, -1), (-1, 0), (0, 1), (1, 0)}.
Terms
- a(0) =1a(1) =0a(2) =1a(3) =2a(4) =2a(5) =13a(6) =21a(7) =67a(8) =231a(9) =509a(10) =1947a(11) =5522a(12) =16637a(13) =58030a(14) =170547a(15) =579290a(16) =1896475a(17) =6081303a(18) =20884509a(19) =68398930a(20) =231286693a(21) =788124656a(22) =2649341358a(23) =9130259705a(24) =31203913903a(25) =107304612514a(26) =372144639423
External references
- oeis: A151352