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A367873
Irregular triangle read by rows: T(n,k) = number of permutations of length n avoiding simultaneously the patterns 132 and 321 with the maximum number of non-overlapping ascents equal to k.
0
1, 1, 1, 0, 4, 0, 4, 3, 0, 0, 11, 0, 0, 9, 7, 0, 0, 0, 22, 0, 0, 0, 16, 13, 0, 0, 0, 0, 37, 0, 0, 0, 0, 25, 21, 0, 0, 0, 0, 0, 56, 0, 0, 0, 0, 0, 36, 31, 0, 0, 0, 0, 0, 0, 79, 0, 0, 0, 0, 0, 0, 49, 43, 0, 0, 0, 0, 0, 0, 0, 106
OFFSET
0,5
COMMENTS
An ascent in a permutation a(1)a(2)...a(n) is position i such that a(i) < a(i+1).
FORMULA
G.f.: (1 + x + x^2 - 2*x^2*y + x^3*y + x^4*y + 3*x^4*y^2 + 2*x^5*y^2)/(1 - x^2*y)^3.
EXAMPLE
1,
1, 1,
0, 4,
0, 4, 3,
0, 0, 11,
0, 0, 9, 7,
0, 0, 0, 22,
0, 0, 0, 16, 13,
0, 0, 0, 0, 37,
0, 0, 0, 0, 25, 21,
0, 0, 0, 0, 0, 56,
0, 0, 0, 0, 0, 36, 31,
0, 0, 0, 0, 0, 0, 79,
0, 0, 0, 0, 0, 0, 49, 43,
0, 0, 0, 0, 0, 0, 0, 106
CROSSREFS
Cf. A367631.
Sequence in context: A135031 A238002 A361618 * A016680 A062524 A152856
KEYWORD
nonn,tabf
AUTHOR
Tian Han, Dec 03 2023
STATUS
approved