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a(0)=0; a(1)=2. Slowest increasing sequence where every digit "d" has a copy of itself in a(n+d).
2

%I #2 Mar 31 2012 13:46:51

%S 0,2,3,12,13,123,124,132,213,214,1234,1235,1236,1243,1324,1325,1352,

%T 1423,12346,12347,12350,12354,12364,12374,12376,12435,123457,123458,

%U 123459,123460,1234567,1234568,1234569,1234570,1234571,1234586,1234596

%N a(0)=0; a(1)=2. Slowest increasing sequence where every digit "d" has a copy of itself in a(n+d).

%e The copy of the first "2" is to be found in "12", 2 jumps to the right.

%e The copy of the first "3" is to be found in "123", 3 jumps to the right.

%e The copy of the first "1" is to be found in "13", 1 jump to the right, etc.

%e The "3" of "13" comes from the obligation of having the smallest gap between two integers. The same reason explains the apparition of the first "4" (the next integer after 123 is 124). The digit "0" obeys the same rules and doesn't copy itself anywhere, of course.

%K base,easy,nonn

%O 0,2

%A _Eric Angelini_, Feb 15 2005