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A288539
Number of Dyck paths of semilength n such that at least one positive level has no peaks.
2
1, 0, 1, 2, 8, 25, 83, 282, 971, 3386, 11940, 42504, 152546, 551426, 2005930, 7337901, 26976726, 99618976, 369349607, 1374391706, 5131186060, 19214759396, 72152791729, 271629133830, 1024989876797, 3876208984221, 14688301498888, 55763768987236, 212077310097784
OFFSET
0,4
COMMENTS
a(0) = 1 by convention.
LINKS
EXAMPLE
: a(3) = 2:
: /\
: /\/\ / \
: / \ / \ .
CROSSREFS
Column k=0 of A288387.
Cf. A000108.
Sequence in context: A212323 A301842 A240478 * A281338 A036367 A115256
KEYWORD
nonn
AUTHOR
Alois P. Heinz, Jun 11 2017
STATUS
approved