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%I #35 Sep 15 2018 02:04:31
%S 1,2,4,5,9,14,8,10,18,27,17,6,11,15,29,44,19,36,54,35,21,42,23,46,25,
%T 50,28,55,83,112,31,62,33,66,37,72,108,71,39,78,41,82,124,45,89,134,
%U 88,48,96,51,101,152,53,106,160,105,57,114,59,118,61,122,184,64
%N Lexicographically earliest sequence S with property that a(n) is the a(n)-th absolute first difference of S.
%C A kind of self-describing sequence.
%C Recamán's sequence A005132 is also self-describing in this sense, but comes lexicographically after this one (and you have to drop the initial "0").
%C If we want S to be monotonically increasing, we get A063733.
%D Eric Angelini, Posting to Sequence Fans Mailing List, Nov 26, 2010
%e If n = 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 ...
%e a(n) = 1 2 4 5 9 14 8 10 18 27 17, 6 11 15 29 44 19 36 54 35 21 42 23 46 25 50 28 55 ...
%e diff = 1 2 1 4 5 6 2 8 9 10 11 5 4 14 15 25 17 18 19 14 21 19 23 21 25 22
%e d-rank= 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26
%e hit: * * * * * * * * * * * * *
%e S is tricky to compute; the rule for a(n+1) is "always use the smallest integer not yet in S and not leading to a contradiction".
%e '14' is in S and '14' says: "The 14th absolute first difference in S equals 14" -- which is true.
%Y Cf. A005132, A063733.
%K nonn
%O 1,2
%A _Eric Angelini_, Dec 31 2013
%E More terms from _Jon E. Schoenfield_, Jan 11 2014
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