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A241798
Number of ballot sequences of length n having exactly five descents.
2
4, 112, 1615, 15403, 112106, 672015, 3477691, 16037089, 67235292, 260887532, 946435074, 3246205986, 10587385911, 33085654876, 99411959668, 288773319190, 812777159786, 2225529375130, 5937743304924, 15483111029378, 39503358108034, 98849770060367, 242801184657314
OFFSET
9,1
EXAMPLE
a(9) = 4: [1,2,1,3,2,1,3,2,1], [1,2,1,3,2,1,4,2,1], [1,2,1,3,2,1,4,3,1], [1,2,1,3,2,1,4,3,2].
CROSSREFS
Column k=5 of A238121 and of A238122.
Sequence in context: A212655 A181485 A135917 * A158450 A063406 A361543
KEYWORD
nonn
AUTHOR
Joerg Arndt and Alois P. Heinz, Apr 28 2014
STATUS
approved