Number of walks within N^2 (the first quadrant of Z^2) starting at (0,0) and consisting of n steps taken from {(-1, 0), (1, 0), (1, 1)}.
A151281
Number of walks within N^2 (the first quadrant of Z^2) starting at (0,0) and consisting of n steps taken from {(-1, 0), (1, 0), (1, 1)}.
Terms
- a(0) =1a(1) =2a(2) =6a(3) =16a(4) =48a(5) =136a(6) =408a(7) =1184a(8) =3552a(9) =10432a(10) =31296a(11) =92544a(12) =277632a(13) =824448a(14) =2473344a(15) =7365120a(16) =22095360a(17) =65920000a(18) =197760000a(19) =590790656a(20) =1772371968a(21) =5299916800a(22) =15899750400a(23) =47578857472a(24) =142736572416a(25) =427357700096
External references
- oeis: A151281