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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 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,4

COMMENTS

a(0) = 1 by convention.

LINKS

Alois P. Heinz, Table of n, a(n) for n = 0..300

Wikipedia, Counting lattice paths

EXAMPLE

: a(3) = 2:

:                 /\

:        /\/\    /  \

:       /    \  /    \  .

CROSSREFS

Column k=0 of A288387.

Cf. A000108.

Sequence in context: A212323 A301842 A240478 * A281338 A036367 A115256

Adjacent sequences:  A288536 A288537 A288538 * A288540 A288541 A288542

KEYWORD

nonn

AUTHOR

Alois P. Heinz, Jun 11 2017

STATUS

approved

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Last modified December 12 12:30 EST 2019. Contains 329958 sequences. (Running on oeis4.)