Returning walks of length 2n on the upper half of the square lattice, distinct under reflections about the y-axis.
A138552
Returning walks of length 2n on the upper half of the square lattice, distinct under reflections about the y-axis.
Terms
- a(0) =1a(1) =2a(2) =11a(3) =90a(4) =889a(5) =9723a(6) =113322a(7) =1380522a(8) =17382365a(9) =224573349a(10) =2962117366a(11) =39741658047a(12) =540862505806
External references
- oeis: A138552