This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A278554 #30 Dec 26 2021 23:34:25 %S A278554 1,2,4,8,15,29,55,101,175,323,583 %N A278554 Number of distinct blocks of length n (a.k.a. subword complexity) of the characteristic sequence of the squarefree numbers A008966. %C A278554 Conjecture 1: this is the number of binary sequences S of length n such that, for all primes p such that p^2 <= n, at least one of the p^2 linearly indexed subsequences of S with gap p^2 starting at the 1st, 2nd, ..., p^2-th position of S, is the all-zeros sequence. In other words, every block that is not explicitly ruled out by congruence conditions for the primes p with p^2 <= n should occur. %C A278554 Conjecture 2: the last new block to actually occur is always 0^n (n copies of 0). Cf. A020754. %e A278554 For n = 5, the 3 blocks of length 5 that do not occur are 11111, 11110, and 01111. %Y A278554 Cf. A008966, A020754. %K A278554 nonn,more %O A278554 0,2 %A A278554 _Jeffrey Shallit_, Jan 02 2017