Number of walks of length n on square lattice, starting at origin, staying in first and third quadrants.

A060897

Number of walks of length n on square lattice, starting at origin, staying in first and third quadrants.

Terms

    a(0) =1a(1) =4a(2) =12a(3) =44a(4) =144a(5) =528a(6) =1808a(7) =6676a(8) =23536a(9) =87568a(10) =315136a(11) =1180680a(12) =4314560a(13) =16263896a(14) =60138816a(15) =227899484a(16) =850600944a(17) =3238194560a(18) =12177384544a(19) =46542879384a(20) =176110444736a(21) =675431779856

External references