OFFSET
0,2
COMMENTS
A133603 is a companion sequence.
FORMULA
EXAMPLE
a(4) = C(4) = 14.
a(5) = 56 = C(5) + C(4) = 42 + 14.
PROG
(Python)
from sympy import catalan
def a005807(n): return catalan(n) + catalan(n + 1)
def a048990(n): return catalan(2*n)
l=[1, 2]
for n in range(2, 31): l+=[a048990(n//2) if n%2==0 else a005807(n - 1)]
print(l) # Indranil Ghosh, Jul 15 2017
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Gary W. Adamson, Sep 18 2007
STATUS
approved