Number of loops of length 4n on square grid that turn at each step and return to start in original direction.
A000644
Number of loops of length 4n on square grid that turn at each step and return to start in original direction.
Terms
- a(0) =1a(1) =1a(2) =3a(3) =7a(4) =31a(5) =138a(6) =808a(7) =4956a(8) =33047a(9) =227328a(10) =1614793a(11) =11710299a(12) =86495618a(13) =648399937a(14) =4923728056
External references
- oeis: A000644