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).
1, 1, 3, 7, 22, 66, 217, 715, 2438, 8398, 29414, 104006, 371516, 1337220, 4847637
2 seqfan posts
Tue Jan 4 05:30:45 CET 2011 [seqfan] Unlabeled super-Catalan - was unlabeled Motzkin