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Lexicographically earliest sequence of distinct nonnegative integers such that for any n >= 0, a(n) AND a(n+1) equals 0 or a(n) (where AND denotes the bitwise AND operator).
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%I #13 Mar 03 2024 14:13:17

%S 0,1,2,3,4,5,7,8,6,9,11,15,16,10,14,17,12,13,18,19,23,31,32,20,21,29,

%T 34,24,25,27,36,26,30,33,22,40,41,43,47,63,64,28,35,39,55,72,37,45,61,

%U 66,44,46,62,65,38,54,73,48,49,51,59,68,42,58,69,50,76,77

%N Lexicographically earliest sequence of distinct nonnegative integers such that for any n >= 0, a(n) AND a(n+1) equals 0 or a(n) (where AND denotes the bitwise AND operator).

%C This sequence is a permutation of the nonnegative integers (with inverse A370794):- we can always extend the sequence with a power of 2 greater than any prior term,

%C - for any k >= 0, the first term >= 2^k is precisely 2^k,

%C - every power of 2 appears in the sequence, in ascending order,

%C - if a(n) = 2^k and the least value not in the sequence at this point, say v, satisfies v < 2^k, then a(n+1) = v, and eventually every nonnegative integer will appear in the sequence.

%H Rémy Sigrist, <a href="/A370793/b370793.txt">Table of n, a(n) for n = 0..10000</a>

%H Rémy Sigrist, <a href="/A370793/a370793.png">Scatterplot of the first 500000 terms</a>

%H Rémy Sigrist, <a href="/A370793/a370793.txt">C++ program</a>

%H Rémy Sigrist, <a href="/A370793/a370793_1.txt">C++ program (faster)</a>

%H <a href="/index/Per#IntegerPermutation">Index entries for sequences that are permutations of the natural numbers</a>

%e The first terms, alongside the bitwise AND of consecutive terms, are:

%e n a(n) a(n) AND a(n+1)

%e -- ---- ---------------

%e 0 0 0

%e 1 1 0

%e 2 2 2

%e 3 3 0

%e 4 4 4

%e 5 5 5

%e 6 7 0

%e 7 8 0

%e 8 6 0

%e 9 9 9

%e 10 11 11

%e 11 15 0

%e 12 16 0

%o (C++) See Links section.

%Y See and A109812, A303767 and A370790 for similar sequences.

%Y Cf. A370794 (inverse).

%K nonn,base

%O 0,3

%A _Rémy Sigrist_, Mar 02 2024