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A341732
Row 2 of array in A341731.
2
1, 2, 6, 8, 21, 26, 67, 82, 213, 262, 690, 856, 2285, 2858, 7719, 9722, 26517, 33590, 92375, 117570, 325581, 416022, 1158921, 1485798, 4160237, 5348878, 15043722, 19389688, 54747357, 70715338, 200360127, 259289578, 736928277, 955277398, 2722540587, 3534526378, 10098646797
OFFSET
4,2
PROG
(PARI) \\ here cat(n) is A000108(n).
cat(n)={binomial(2*n, n)/(n+1)}
a(n)={if(n%2==0, cat(n/2) + 2*cat(n/2-1) - 3, 2*cat(n\2) - 2)} \\ Andrew Howroyd, Mar 13 2021
CROSSREFS
Sequence in context: A290213 A058775 A103023 * A111247 A045656 A343256
KEYWORD
nonn
AUTHOR
N. J. A. Sloane, Mar 07 2021
EXTENSIONS
Terms a(11) and beyond from Andrew Howroyd, Mar 13 2021
STATUS
approved