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Search: id:A127421
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| A127421 |
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Numbers whose decimal expansion is a concatenation of 2 consecutive increasing numbers. |
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+0
5
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| 1, 12, 23, 34, 45, 56, 67, 78, 89, 910, 1011, 1112, 1213, 1314, 1415, 1516, 1617, 1718, 1819, 1920, 2021, 2122, 2223, 2324, 2425, 2526, 2627, 2728, 2829, 2930, 3031, 3132, 3233, 3334, 3435, 3536, 3637, 3738, 3839, 3940, 4041, 4142, 4243, 4344, 4445, 4546
(list; graph; listen)
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OFFSET
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1,2
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FORMULA
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a(n)=n*10^{1+floor[log(n+1)]}+n+1, with n>=0 - Paolo P. Lava (ppl(AT)spl.at), May 09 2008
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EXAMPLE
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a(1) = "0,1" = 1.
a(13)=1213 because 12 and 13 are two consecutive increasing numbers
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MAPLE
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P:=proc(n) local a, i; for i from 0 by 1 to n do a:=i*10^(1+floor(evalf(log10(i+1), 10)))+i+1; print(a); od; end: P(100); - Paolo P. Lava (ppl(AT)spl.at), May 09 2008
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CROSSREFS
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A variant of A001704. Cf. A127421-A127430.
Sequence in context: A072485 A035333 A001704 this_sequence A112131 A088997 A049852
Adjacent sequences: A127418 A127419 A127420 this_sequence A127422 A127423 A127424
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KEYWORD
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nonn,base,easy
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AUTHOR
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Artur Jasinski (grafix(AT)csl.pl), Jan 14 2007
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EXTENSIONS
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More terms from Joshua Zucker (joshua.zucker(AT)stanfordalumni.org), May 15 2007
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