a(n) is the number of n-step walks on square lattice such that 0 <= y <= x at each step.
A005558
a(n) is the number of n-step walks on square lattice such that 0 <= y <= x at each step.
Terms
- a(0) =1a(1) =1a(2) =3a(3) =6a(4) =20a(5) =50a(6) =175a(7) =490a(8) =1764a(9) =5292a(10) =19404a(11) =60984a(12) =226512a(13) =736164a(14) =2760615a(15) =9202050a(16) =34763300a(17) =118195220a(18) =449141836a(19) =1551580888a(20) =5924217936a(21) =20734762776a(22) =79483257308a(23) =281248448936
External references
- oeis: A005558