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A137465
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1 concatenated with n n's concatenated with 1.
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0
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111, 1221, 13331, 144441, 1555551, 16666661, 177777771, 1888888881, 19999999991, 1101010101010101010101, 111111111111111111111111, 11212121212121212121212121, 1131313131313131313131313131, 114141414141414141414141414141, 11515151515151515151515151515151
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OFFSET
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1,1
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LINKS
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Table of n, a(n) for n=1..15.
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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, May 08 2008
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EXAMPLE
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a(7) = 177777771.
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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, May 08 2008
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MATHEMATICA
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Table[FromDigits[Join[{1}, Flatten[IntegerDigits/@Table[n, {n}]], {1}]], {n, 15}] (* Harvey P. Dale, Apr 19 2013 *)
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CROSSREFS
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Cf. A000461 (concatenate n n times).
Sequence in context: A102782 A302475 A303256 * A101152 A250145 A075859
Adjacent sequences: A137462 A137463 A137464 * 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, Apr 19 2008
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EXTENSIONS
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More terms from Harvey P. Dale, Apr 19 2013
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STATUS
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approved
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