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A243878
Number of Dyck paths of semilength n having exactly 8 (possibly overlapping) occurrences of the consecutive steps UDUUUDDDUD (with U=(1,1), D=(1,-1)).
2
1, 10, 73, 490, 3127, 19249, 115021, 669745, 3812716, 21277658, 116666435, 629665898, 3350420024, 17599292330, 91368992279, 469293511892, 2386777084592, 12029136326922, 60118399193577, 298121360285805, 1467661404628893, 7176555449003580, 34870090954789419
OFFSET
33,2
LINKS
MAPLE
b:= proc(x, y, t) option remember; `if`(y<0 or y>x, 0, `if`(x=0, 1,
series(b(x-1, y+1, [2, 2, 4, 5, 6, 2, 4, 2, 10, 2][t])+`if`(t=10,
z, 1)*b(x-1, y-1, [1, 3, 1, 3, 3, 7, 8, 9, 1, 3][t]), z, 9)))
end:
a:= n-> coeff(b(2*n, 0, 1), z, 8):
seq(a(n), n=33..60);
CROSSREFS
Column k=8 of A243881.
Sequence in context: A161743 A016211 A055424 * A200580 A181678 A206817
KEYWORD
nonn
AUTHOR
Alois P. Heinz, Jun 13 2014
STATUS
approved