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Search: id:A073778
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| A073778 |
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a(n)=Sum(T(k)T(n-k)), k=0,..,n. Convolution of tribonacci sequence A000073 with itself. |
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+0
2
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| 0, 0, 1, 2, 5, 12, 26, 56, 118, 244, 499, 1010, 2027, 4040, 8004, 15776, 30956, 60504, 117845, 228818, 443057, 855732, 1649022, 3171128, 6086626, 11662252, 22309543, 42614178, 81286743, 154856528, 294660040, 560052736, 1063367384, 2017030256
(list; graph; listen)
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OFFSET
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0,4
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COMMENT
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Number of binary sequences of length n+1 that have exacly one subsequence 000. Example: a(4)=5 because because we have 00010,00011,01000,10001, and 11000. Column 1 of A118390. - Emeric Deutsch (deutsch(AT)duke.poly.edu), Apr 27 2006
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FORMULA
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G.f.: x^2/(1-x-x^2-x^3)^2
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MATHEMATICA
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CoefficientList[Series[x^2/(1-x-x^2-x^3)^2, {x, 0, 40}], x]
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CROSSREFS
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Cf. A000073.
Cf. A118390.
Adjacent sequences: A073775 A073776 A073777 this_sequence A073779 A073780 A073781
Sequence in context: A026688 A116726 A125180 this_sequence A033490 A116716 A128812
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KEYWORD
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easy,nonn
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AUTHOR
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Mario Catalani (mario.catalani(AT)unito.it), Aug 10 2002
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