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A243772
Number of Dyck paths of semilength n having exactly three (possibly overlapping) occurrences of the consecutive step pattern given by the binary expansion of n, where 1=U=(1,1) and 0=D=(1,-1).
3
4, 5, 35, 0, 280, 1991, 4115, 34840, 96286, 309036, 1045200, 193240, 5159120, 40653929, 105545340, 603157520, 2582073261, 11015773404, 26828044860, 182118031760, 726122370210, 3026319516720, 9620891607824, 49247195403600, 161316665871200, 638742288482240
OFFSET
5,1
LINKS
EXAMPLE
a(5) = 4: UDUDUDUUDD, UDUDUUDUDD, UDUUDUDUDD, UUDUDUDUDD.
a(6) = 5: UUDDUUDDUUDD, UUDDUUDUUDDD, UUDUUDDDUUDD, UUDUUDDUUDDD, UUDUUDUUDDDD.
CROSSREFS
Column k=3 of A243752.
Main diagonal of A243829.
Sequence in context: A041907 A228662 A151450 * A332316 A243275 A269782
KEYWORD
nonn
AUTHOR
Alois P. Heinz, Jun 10 2014
STATUS
approved