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Search: id:A103771
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| A103771 |
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Expansion of 1/(1-4x-4x^2-4x^3). |
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1
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| 1, 4, 20, 100, 496, 2464, 12240, 60800, 302016, 1500224, 7452160, 37017600, 183879936, 913398784, 4537185280, 22537856000, 111953760256, 556115206144, 2762427289600, 13721985024000, 68162110078976, 338586089570304
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OFFSET
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0,2
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COMMENT
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The sequence with g.f. 1/(1-r*x-r*x^2-r*x^3) has general term sum{k=0..n, T(n-k,k)r^(n-k)}.
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FORMULA
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a(n)=sum{k=0..n, T(n-k, k)4^(n-k)}, T(n, k) = trinomial coefficients (A027907)
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CROSSREFS
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Cf. A077828, A077835, A000073.
Adjacent sequences: A103768 A103769 A103770 this_sequence A103772 A103773 A103774
Sequence in context: A057087 A098225 A073532 this_sequence A005054 A105480 A082761
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KEYWORD
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easy,nonn
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AUTHOR
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Paul Barry (pbarry(AT)wit.ie), Feb 15 2005
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