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, -1), (1, 0), (1, 1)}.
A151291
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, -1), (1, 0), (1, 1)}.
Terms
- a(0) =1a(1) =2a(2) =7a(3) =23a(4) =84a(5) =301a(6) =1127a(7) =4186a(8) =15891a(9) =60128a(10) =230334a(11) =881299a(12) =3397561a(13) =13095693a(14) =50725377a(15) =196537671a(16) =764061552a(17) =2971863841a(18) =11587071431a(19) =45203638492a(20) =176663521046a(21) =690848304886
External references
- oeis: A151291