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, 1)}.
A151353
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, 1)}.
Terms
- a(0) =1a(1) =0a(2) =1a(3) =2a(4) =2a(5) =14a(6) =21a(7) =76a(8) =252a(9) =566a(10) =2282a(11) =6248a(12) =19958a(13) =69356a(14) =205129a(15) =720868a(16) =2340178a(17) =7692570a(18) =26681224a(19) =87814024a(20) =302838250a(21) =1035805496a(22) =3526054994a(23) =12286338876a(24) =42255768876a(25) =147090631152a(26) =513835481206
External references
- oeis: A151353