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Search: id:A005324
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| 1, 5, 20, 70, 230, 726, 2235, 6765, 20240, 60060, 177177, 520455, 1524120, 4453320, 12991230, 37854954, 110218905, 320751445, 933149470, 2714401580, 7895719634, 22969224850, 66829893650, 194486929650, 566141346225, 1648500576021
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OFFSET
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4,2
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COMMENT
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a(n) = number of (s(0), s(1), ..., s(n)) such that s(i) is a nonnegative integer and |s(i) - s(i-1)| <= 1 for i = 1,2,...,n, s(0) = 0, s(n) = 4. - Clark Kimberling (ck6(AT)evansville.edu)
a(n) = T(n,n-4), where T is the array in A026300.
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REFERENCES
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R. Donaghey and L. W. Shapiro, Motzkin numbers, J. Combin. Theory, Series A, 23 (1977), 291-301.
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FORMULA
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G.f.: z^4*M^5, where M is g.f. of Motzkin numbers (A001006).
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CROSSREFS
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Cf. A026300.
A diagonal of triangle A020474.
Adjacent sequences: A005321 A005322 A005323 this_sequence A005325 A005326 A005327
Sequence in context: A089094 A080930 A000343 this_sequence A054889 A056384 A036683
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KEYWORD
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nonn,easy
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AUTHOR
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njas
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