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Search: id:A132583
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| A132583 |
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a(n) = n 2's sandwiched between two 1's. |
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+0
1
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| 11, 121, 1221, 12221, 122221, 1222221, 12222221, 122222221, 1222222221, 12222222221, 122222222221, 1222222222221, 12222222222221, 122222222222221, 1222222222222221, 12222222222222221, 122222222222222221
(list; graph; listen)
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OFFSET
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0,1
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FORMULA
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a(0) = 0; a(n) = 10*a(n-1)+11. - Jonathan Vos Post (jvospost3(AT)gmail.com), Nov 24 2007
O.g.f.: 11/((-1+x)*(-1+10*x)) = -(110/9)/(-1+10*x)+(11/9)/(-1+x) . - R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Nov 28 2007
a(n)=20*(10^n-1)/9+10^(n+1)+1, with n>=0 - Paolo P. Lava (ppl(AT)spl.at), Dec 19 2007
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CROSSREFS
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Sequence in context: A033867 A106473 A125315 this_sequence A007907 A088113 A045587
Adjacent sequences: A132580 A132581 A132582 this_sequence A132584 A132585 A132586
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KEYWORD
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nonn
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AUTHOR
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Paul Curtz (bpcrtz(AT)free.fr), Nov 21 2007
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