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Search: id:A026379
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| A026379 |
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a(n) = number of integer strings s(0),...,s(n) counted by array T in A026374 that have s(n)=3; also a(n)=T(2n-1,n-2). |
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+0
2
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| 1, 7, 39, 202, 1015, 5028, 24731, 121208, 593019, 2899335, 14173401, 69301422, 338990145, 1659037695, 8124085575, 39806373880, 195160896835, 957396540285, 4699409632805, 23080158080150, 113414575414245, 557601196738190
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OFFSET
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2,2
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FORMULA
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a(n)=[t^(n+1)]{(1+t)(1+3t+t^2)^(n-1)}. - Emeric Deutsch (deutsch(AT)duke.poly.edu), Jan 30 2004
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MAPLE
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sum(binomial(n, k)*binomial(2*k+1, k-1), k=0..n); n=0, 1, ... [ njas ]
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CROSSREFS
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Partial sums of A034942.
Sequence in context: A081898 A034267 A026752 this_sequence A026708 A016127 A099460
Adjacent sequences: A026376 A026377 A026378 this_sequence A026380 A026381 A026382
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KEYWORD
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nonn,nice,easy
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AUTHOR
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Clark Kimberling (ck6(AT)evansville.edu)
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