Number of walks within N^2 (the first quadrant of Z^2) starting at (0,0) and consisting of n steps taken from {(-1, 1), (-1, 0), (0, -1), (0, 1), (1, -1)}.
A151268
Number of walks within N^2 (the first quadrant of Z^2) starting at (0,0) and consisting of n steps taken from {(-1, 1), (-1, 0), (0, -1), (0, 1), (1, -1)}.
Terms
- a(0) =1a(1) =1a(2) =3a(3) =7a(4) =23a(5) =69a(6) =241a(7) =815a(8) =2973a(9) =10765a(10) =40599a(11) =153519a(12) =594441a(13) =2315819a(14) =9159005a(15) =36470431a(16) =146745519a(17) =594261517a(18) =2425275509a(19) =9954790549a(20) =41110526691a(21) =170626390065a(22) =711716332495
External references
- oeis: A151268