A338760 - OEIS

%I #5 Nov 07 2020 08:48:38

%S 1,2,4,8,15,28,47,73,107,150,203,267,343,432,535,653,787,938,1107,

%T 1295,1503,1732,1983,2257,2555,2878,3227,3603,4007,4440,4903,5397,

%U 5923,6482,7075,7703,8367,9068,9807,10585,11403,12262,13163,14107,15095,16128,17207

%N Subword complexity of a certain infinite word.

%C The infinite word is (ab)(aab.abb)(aaab.aabb.abbb)(aaaab.aaabb.aabbb.abbbb)... . Subword complexity is the number of distinct length-n blocks appearing in the sequence.

%H L. Schaeffer and K. Wu, <a href="https://cs.uwaterloo.ca/journals/JIS/VOL23/Wu/wu3.html">Two Infinite Words with Cubic Subword Complexity</a>, J. Integer Sequences 23 (2020), Paper 20.10.8.

%F Equal to 2^n for n <= 3, and n^3/6+n^2/2-5n/3+3 for n >= 4.

%e For n=4 the only word omitted is baba.

%Y Cf. A338761.

%K nonn

%O 0,2

%A _Jeffrey Shallit_, Nov 07 2020