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 A106004 First monotonically increasing sequence such that erasing the first and last digit of each term and concatenating what is left results in the concatenation of all terms of the sequence. 1

%I

%S 110,111,200,210,211,212,220,300,400,420,510,600,620,710,711,720,810,

%T 820,822,823,900,930,1000,1400,2040,2200,2510,3060,4000,4620,5070,

%U 6100,6710,7170,7200,7810,8080,8200,9280,12390,20090,23010

%N First monotonically increasing sequence such that erasing the first and last digit of each term and concatenating what is left results in the concatenation of all terms of the sequence.

%C Could one say this is kind of fractal?

%e To avoid numbers beginning with 0, we assume the first term is 1xy, and so x=1, so 11y, but y=0 works, so the first term is 110.

%e The next two terms must be a1b, c0d, and se we take a=b=1, c=2, d=0, so now the sequence begins 110, 111, 200. And so on.

%Y Cf. A106003.

%K base,easy,nonn

%O 1,1

%A _Eric Angelini_, Apr 29 2005

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Last modified January 23 08:42 EST 2019. Contains 319375 sequences. (Running on oeis4.)