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A self-descriptive fractal sequence: the sequence contains every positive integer. If the first occurrence of each integer is deleted from the sequence, the resulting sequence is the same as the original (this process may be called "upper trimming").
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%I #7 Jan 18 2020 20:32:58

%S 1,1,2,1,3,2,1,4,3,5,2,1,4,6,3,5,7,2,8,1,4,6,3,9,5,7,2,10,8,1,4,6,3,

%T 11,9,5,12,7,13,2,10,8,1,14,4,6,3,11,9,5,15,12,7,13,16,2,10,8,1,14,17,

%U 4,6,3,11,9,5,15,18,12,7,19,13,16,2,10,8,1,14,17,20,4,21,6,3,11

%N A self-descriptive fractal sequence: the sequence contains every positive integer. If the first occurrence of each integer is deleted from the sequence, the resulting sequence is the same as the original (this process may be called "upper trimming").

%C This sequence gives the number of numbers that are retained between Xs that are dropped (cf. the example in A112382). Alternatively, each term is the number of numbers between first two occurrences of integers. For example, the first 3 describes the three numbers 2, 1, 4 between the first 5 and the first 6.

%Y Cf. A112377, A112382, A112384.

%K nonn

%O 0,3

%A _Kerry Mitchell_, Dec 05 2005