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), (-1, 1), (0, -1), (0, 1), (1, 0)}.
A151368
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), (-1, 1), (0, -1), (0, 1), (1, 0)}.
Terms
- a(0) =1a(1) =0a(2) =2a(3) =3a(4) =12a(5) =40a(6) =145a(7) =560a(8) =2240a(9) =9156a(10) =38724a(11) =166320a(12) =728508a(13) =3239808a(14) =14595438a(15) =66543477a(16) =306511920a(17) =1424916064a(18) =6679435048a(19) =31544500416a(20) =149986398848a(21) =717562911000
External references
- oeis: A151368