OFFSET
1,2
COMMENTS
Since Catalan(n) enumerates so many different things, natural upper bounds like this and A006516 are candidates for counting objects not having some property.
PROG
(Python)
from sympy import catalan
def A342906(n): return 2**(2*n-2)-catalan(n) # Chai Wah Wu, Apr 01 2021
CROSSREFS
KEYWORD
nonn
AUTHOR
N. J. A. Sloane, Mar 31 2021
STATUS
approved