171529836218
domain: N
Appears in sequences
- a(n) = C_n / 2 if n is even or ( C_n + C_((n-1)/2) ) / 2 if n is odd, where C = Catalan numbers (A000108).at n=22A007595
- Number of plane trees with even number of leaves.at n=22A071688
- Number of cycles in range [A014137(n-1)..A014138(n-1)] of permutation A089864.at n=23A089402
- Number of cycles in range [A014137(n-1)..A014138(n-1)] of permutation A069772.at n=23A089880