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, 1), (1, 0), (1, 1)}.
A151289
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, 1), (1, 0), (1, 1)}.
Terms
- a(0) =1a(1) =2a(2) =7a(3) =21a(4) =80a(5) =267a(6) =1042a(7) =3655a(8) =14400a(9) =51960a(10) =205770a(11) =756169a(12) =3003754a(13) =11179972a(14) =44496878a(15) =167181919a(16) =666257284a(17) =2521360818a(18) =10057256094a(19) =38278262216a(20) =152783755958a(21) =584199222356
External references
- oeis: A151289