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Search: id:A131051
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| 1, 3, 8, 18, 38, 78, 158, 318, 638, 1278, 2558, 5118, 10238, 20478, 40958, 81918, 163838, 327678, 655358, 1310718, 2621438, 5242878, 10485758, 20971518, 41943038, 83886078, 167772158, 335544318, 671088638, 1342177278, 2684354558
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OFFSET
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1,2
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FORMULA
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Binomial transform of [1, 2, 3, 2, 3, 2, 3,...].
O.g.f.: (1+x^2)/((1-x)(1-2*x)). a(n)=A051633(n-2). - R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Jun 13 2008
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EXAMPLE
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a(4) = 18 = sum of row 4 terms of triangle A133805: (7 + 6 + 4 + 1).
a(4) = 18 = (1, 3, 3, 1), dot (1, 2, 3, 2) = (1 + 6 + 9 + 2).
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MATHEMATICA
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a=8; lst={1, 3, a}; k=10; Do[a+=k; AppendTo[lst, a]; k+=k, {n, 0, 5!}]; lst [From Vladimir Orlovsky (4vladimir(AT)gmail.com), Dec 17 2008]
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CROSSREFS
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Cf. A133805.
Sequence in context: A006478 A104187 A051633 this_sequence A117727 A117713 A128552
Adjacent sequences: A131048 A131049 A131050 this_sequence A131052 A131053 A131054
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KEYWORD
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nonn
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AUTHOR
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Gary W. Adamson (qntmpkt(AT)yahoo.com), Sep 23 2007
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EXTENSIONS
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More terms from R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Jun 13 2008
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