Number of 2n-step walks on square lattice starting and ending at the origin with first step north and avoiding early returns.

A366924

Number of 2n-step walks on square lattice starting and ending at the origin with first step north and avoiding early returns.

Terms

    a(0) =1a(1) =5a(2) =44a(3) =469a(4) =5516a(5) =68892a(6) =896016a(7) =11998869a(8) =164259308a(9) =2287663804a(10) =32303714576a(11) =461352451292

External references