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 A230177 #15 Jan 22 2020 14:38:33 %S A230177 1,2,4,8,16,32,64,128,240,464,866,1642,3048,5720,10642,19868,36894, %T A230177 68722,127630,237324,440594,818584,1519802,2822630,5240262,9730478, %U A230177 18065252,33542006,62272196,115616582,214646190,398507348,739840164,1373551484,2550032248 %N A230177 Number of binary strings of length n avoiding "squares" (that is, repeated blocks of the form xx) with |x| > 3. %H A230177 R. C. Entringer, D. E. Jackson and J. A. Schatz, <a href="https://doi.org/10.1016/0097-3165(74)90041-7">On nonrepetitive sequences</a>, J. Combin. Theory Ser. A. 16 (1974), 159-164. %H A230177 Nathaniel Johnston, <a href="/A230177/a230177.c.txt">C code for computing this sequence</a> %e A230177 a(8) = 256 - 16 = 240 because there are 256 binary strings of length 8, 16 of which contain a repeated block of length 4: 00000000, 00010001, 00100010, ..., 11111111. %Y A230177 Cf. A229614, A230127, A230216. %K A230177 nonn %O A230177 0,2 %A A230177 _Nathaniel Johnston_, Oct 11 2013