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Search: id:A137465
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| A137465 |
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1 concatenated with n n's concatenated with 1. |
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+0
1
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| 111, 1221, 13331, 144441, 1555551, 16666661, 177777771, 1888888881, 19999999991, 1101010101010101010101, 111111111111111111111111, 11212121212121212121212121
(list; graph; listen)
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OFFSET
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1,1
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FORMULA
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a(n)=10^{1+n*[1+floor(log(n))]}+10*Sum{k=0..n-1}{n+10^[1+floor(log(n))]*k}+1, with n>=1 - Paolo P. Lava (ppl(AT)spl.at), May 08 2008
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EXAMPLE
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a(7)= 1 7 7 7 7 7 7 7 1
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MAPLE
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P:=proc(n) local a, i, k; for i from 1 by 1 to n do a:=10^(1+i*(1+floor(evalf(log10(i), 10))))+10*sum(i*10^((1+floor(evalf(log10(i), 10)))*k), 'k'=0..(i-1))+1; print(a); od; end: P(30); - Paolo P. Lava (ppl(AT)spl.at), May 08 2008
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CROSSREFS
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Sequence in context: A115816 A115877 A102782 this_sequence A101152 A075859 A008396
Adjacent sequences: A137462 A137463 A137464 this_sequence A137466 A137467 A137468
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KEYWORD
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easy,nonn,base
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AUTHOR
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Ctibor O. Zizka (ctibor.zizka(AT)seznam.cz), Apr 19 2008
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