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, 0), (-1, 1), (0, 1), (1, -1)}.
A151401
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, 0), (-1, 1), (0, 1), (1, -1)}.
Terms
- a(0) =1a(1) =1a(2) =1a(3) =3a(4) =7a(5) =15a(6) =45a(7) =123a(8) =341a(9) =1055a(10) =3143a(11) =9687a(12) =30859a(13) =97483a(14) =315861a(15) =1033493a(16) =3395089a(17) =11316469a(18) =37893747a(19) =127757627a(20) =434147079a(21) =1481301463a(22) =5084504675a(23) =17536498671a(24) =60720379293a(25) =211194514011a(26) =737154897245
External references
- oeis: A151401