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A106003
Keep only the middle digit of each integer and concatenate them. The result is the concatenation of all integers of the sequence.
1
0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 110, 111, 200, 210, 211, 212, 220, 300, 400, 420, 510, 600, 620, 710, 711, 720, 810, 820, 822, 823, 900, 930, 10000, 10001, 10400, 11000, 11001, 11400, 12200, 13000, 13500, 14100, 15000, 15600, 16000, 16001, 16600, 17200
OFFSET
0,3
COMMENTS
Could one say this is kind of fractal?
The definition seems to be the following: all terms have an odd number of digits, and are strictly increasing. Now delete all except the middle digits of each term. The result is the succession of digits of all the terms. We take the lexicographically earliest sequence satisfying these conditions. - N. J. A. Sloane, Aug 09 2012
CROSSREFS
Cf. A106004.
Sequence in context: A028431 A181352 A056143 * A283868 A087995 A082232
KEYWORD
base,easy,nonn
AUTHOR
Eric Angelini, Apr 29 2005
STATUS
approved