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A075859
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a(n) = n concatenated with n 1's and n.
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0
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111, 2112, 31113, 411114, 5111115, 61111116, 711111117, 8111111118, 91111111119, 10111111111110, 111111111111111, 1211111111111112, 13111111111111113, 141111111111111114, 1511111111111111115, 16111111111111111116, 171111111111111111117, 1811111111111111111118
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graph;
refs;
listen;
history;
text;
internal format)
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OFFSET
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1,1
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COMMENTS
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All terms are divisible by 3. - Donald Sampson (marsquo(AT)hotmail.com), Dec 09 2003
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REFERENCES
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J. Earls, On Smarandache Repunit N Numbers, Smarandache Notions Journal
(2004), Vol. 14.1, pp 251-258.
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LINKS
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FORMULA
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a(n) = n * 10^(n+L) + 10^L * R + n, where R is the n-th repunit and L is the number of decimal digits of n.
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MATHEMATICA
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Array[FromDigits@ Join[#1, #2, #1] & @@ {IntegerDigits[#], ConstantArray[1, #]} &, 16] (* Michael De Vlieger, Mar 21 2018 *)
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CROSSREFS
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KEYWORD
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base,easy,nonn,less
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AUTHOR
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EXTENSIONS
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More terms from Donald Sampson (marsquo(AT)hotmail.com), Dec 09 2003
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STATUS
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approved
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