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, 1), (0, 1), (1, 0)}.
A151391
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, 1), (0, 1), (1, 0)}.
Terms
- a(0) =1a(1) =1a(2) =2a(3) =6a(4) =16a(5) =45a(6) =142a(7) =452a(8) =1429a(9) =4706a(10) =15830a(11) =53092a(12) =180380a(13) =622747a(14) =2155976a(15) =7495821a(16) =26308397a(17) =92778770a(18) =327973373a(19) =1165333486a(20) =4159080037a(21) =14877633175a(22) =53376247653a(23) =192149069209a(24) =693285668555
External references
- oeis: A151391