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Search: id:A141355
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| A141355 |
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The Jacobsthal sequence, dropping each third term. |
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+0
1
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| 1, 1, 5, 11, 43, 85, 341, 683, 2731, 5461, 21845, 43691, 174763, 349525, 1398101, 2796203, 11184811, 22369621, 89478485, 178956971, 715827883, 1431655765, 5726623061, 11453246123, 45812984491, 91625968981, 366503875925, 733007751851
(list; graph; listen)
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OFFSET
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0,3
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COMMENT
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A001045 after removal of the subsequence A132805.
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FORMULA
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a(2n+1)-a(2n) = 6*A015565(n).
a(4n+1)=2a(4n)-1. a(4n+2)=4a(4n+1)+1. a(4n+3)=2a(4n+2)+1. a(4n+4)=4a(4n+3)-1.
a(2n)= A082311(n). a(2n+1) = A082365(n). - R. J. Mathar, Feb 23 2009
a(n)=7*a(n-2)+8*a(n-4). G.f.: (1+x-2*x^2+4*x^3)/((1-8*x^2)*(1+x^2)). - R. J. Mathar, Feb 23 2009
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CROSSREFS
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Sequence in context: A006382 A055113 A129015 this_sequence A097056 A092358 A079029
Adjacent sequences: A141352 A141353 A141354 this_sequence A141356 A141357 A141358
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KEYWORD
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nonn,easy
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AUTHOR
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Paul Curtz (bpcrtz(AT)free.fr), Aug 03 2008
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EXTENSIONS
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Edited and extended by R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Feb 23 2009
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