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A001703
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Decimal concatenation of n, n+1, and n+2.
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9
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12, 123, 234, 345, 456, 567, 678, 789, 8910, 91011, 101112, 111213, 121314, 131415, 141516, 151617, 161718, 171819, 181920, 192021, 202122, 212223, 222324, 232425, 242526, 252627, 262728, 272829, 282930, 293031, 303132, 313233, 323334, 333435, 343536, 353637, 363738
(list;
graph;
refs;
listen;
history;
text;
internal format)
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OFFSET
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0,1
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COMMENTS
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All terms are divisible by 3. Every third term starting with a(2) is divisible by 9. - Alonso del Arte, May 27 2013
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LINKS
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FORMULA
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The portion of the sequence with all three numbers having d digits - i.e., n in 10^(d-1)..10^d-3 - is in arithmetic sequence: a(n) = (10^(2*d)+10^d+1)*n + (10^d+2). - Franklin T. Adams-Watters, Oct 07 2011
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EXAMPLE
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a(8) = 8910 since the three consecutive numbers starting with 8 are 8, 9, 10, and these concatenate to 8910. (This is the first term that differs from A193431).
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MAPLE
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read(transforms) :
digcatL([n, n+1, n+2]) ;
end proc:
# Third Maple program:
a:= n-> parse(cat(n, n+1, n+2)):
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MATHEMATICA
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concat3Nums[n_] := FromDigits@ Flatten@ IntegerDigits[{n, n + 1, n + 2}]; Array[concat3Nums, 25] (* Robert G. Wilson v *)
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PROG
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(Python) for n in range(100): print(int(str(n)+str(n+1)+str(n+2))) # David F. Marrs, Sep 18 2018
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CROSSREFS
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KEYWORD
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nonn,base,easy
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AUTHOR
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mag(AT)laurel.salles.entpe.fr
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EXTENSIONS
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STATUS
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approved
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