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), (0, 1), (1, -1)}.
A151381
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), (0, 1), (1, -1)}.
Terms
- a(0) =1a(1) =1a(2) =1a(3) =2a(4) =4a(5) =8a(6) =18a(7) =41a(8) =97a(9) =236a(10) =584a(11) =1474a(12) =3770a(13) =9767a(14) =25575a(15) =67592a(16) =180128a(17) =483502a(18) =1306308a(19) =3549830a(20) =9697162a(21) =26615698a(22) =73366980a(23) =203034787a(24) =563901485a(25) =1571351150a(26) =4392057592a(27) =12310850747a(28) =34597448119a(29) =97466655175
External references
- oeis: A151381