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%I #3 Mar 31 2012 13:46:52
%S 5,6,7,8,9,15,16,17,18,29,42,63,74,83,161,273,286,300,400,684,900,
%T 1315,1319,1513,1813,1913,2582,3005,3006,3007,3161,3187,3600,3928,
%U 4200,5429,6251,7126,12147,16143,19134,20024,39003,40000,40003,40031,41001,41009
%N A Langford-like sequence.
%C Construction rules: 1) a(n) < a(n+1) 2) if you pick any digit "d" of the sequence, the closest identical one is at exactly "d" digits from it (jumping to the right or to the left).
%e Pick the leftmost "5" and jump 5 digits (to the right): you'll land on another "5".
%e Pick the third "6" (visible in 63) and jump 6 digits (to the right): you'll land on another "6" (161). [Jumping again 6 digits from there to the right would send you on another "6" (286), which is allowed].
%e Pick the first "0" (300) and jump 0 digits (to the right): you'll move to the next digit, which is a "0".
%e Note that the rule (2) forbids integers like "323" because if you pick one of those 3's the *closest* copy is at a "1" jump -- and not at a "3" jump, which is mandatory.
%K base,easy,nonn
%O 5,1
%A _Eric Angelini_, Jul 03 2005
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