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, -1), (1, 1)}.
A151370
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, -1), (1, 1)}.
Terms
- a(0) =1a(1) =0a(2) =2a(3) =3a(4) =20a(5) =60a(6) =345a(7) =1400a(8) =7770a(9) =36876a(10) =204876a(11) =1062600a(12) =5984352a(13) =32772168a(14) =187727826a(15) =1065491427a(16) =6206538910a(17) =36123454224a(18) =213645926208
External references
- oeis: A151370