Number of walks within N^2 (the first quadrant of Z^2) starting at (0,0), ending on the vertical axis and consisting of n steps taken from {(-1, -1), (-1, 0), (0, 1), (1, -1)}.
A151385
Number of walks within N^2 (the first quadrant of Z^2) starting at (0,0), ending on the vertical axis and consisting of n steps taken from {(-1, -1), (-1, 0), (0, 1), (1, -1)}.
Terms
- a(0) =1a(1) =1a(2) =1a(3) =2a(4) =6a(5) =12a(6) =25a(7) =77a(8) =215a(9) =511a(10) =1466a(11) =4610a(12) =12680a(13) =35579a(14) =113158a(15) =344542a(16) =997244a(17) =3112862a(18) =9956308a(19) =30277199a(20) =93800266a(21) =303919846a(22) =963863561a(23) =3017836845a(24) =9766363338a(25) =31766793517a(26) =101462348434a(27) =328277090248
External references
- oeis: A151385