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A135643
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Straight-line numbers > 99.
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11
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111, 123, 135, 147, 159, 210, 222, 234, 246, 258, 321, 333, 345, 357, 369, 420, 432, 444, 456, 468, 531, 543, 555, 567, 579, 630, 642, 654, 666, 678, 741, 753, 765, 777, 789, 840, 852, 864, 876, 888, 951, 963, 975, 987, 999, 1111, 1234
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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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Numbers with more than two digits whose digits are in arithmetic progression. The structure of digits represent a straight line. In the graphic representation the points are connected by imaginary line segments. For a(1) to a(45) this sequence is equal to A034840. If the member of this sequence is greater than 9876543210 then the member is a repdigit number A010785.
Note that the sequence of straight-line numbers starts: 10, 11, 12, ..., 98, 99, 111, 123,... The integers with 2 digits are always straight-line numbers, but here the numbers < 100 are omitted. [From Omar E. Pol, Nov 14 2009]
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LINKS
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Table of n, a(n) for n=1..47.
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EXAMPLE
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The number 3579 is straight-line number:
. . . 9
. . . .
. . 7 .
. . . .
. 5 . .
. . . .
3 . . .
. . . .
. . . .
. . . .
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MATHEMATICA
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Select[Range[100, 1300], Length[Union[Differences[IntegerDigits[#]]]]==1&] (* From Harvey P. Dale, May 09 2012 *)
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CROSSREFS
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Cf. A010785, A034840.
Cf. A135600, A135601, A135602, A135603, A135641, A135642, A163278, A167847. [From Omar E. Pol, Nov 14 2009]
Sequence in context: A222724 A039990 A034840 * A070798 A213879 A095613
Adjacent sequences: A135640 A135641 A135642 * A135644 A135645 A135646
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KEYWORD
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nonn,base
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AUTHOR
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Omar E. Pol, Nov 30 2007, Dec 09 2008, Nov 14 2009
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STATUS
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approved
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