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 A357305 #14 Nov 30 2022 14:55:23 %S A357305 2,3,5,11,45,181,48589783221,66537313397,398064946368587, %T A357305 796095014224053 %N A357305 Numbers k > 1 such that the ratio (numbers of zeros)/(total length) in the binary representation of k^2 is a new minimum. %e A357305 k k^2 (binary zeros)/A070939(k^2) %e A357305 . . . k^2 written in binary %e A357305 2 4 2/3 [1, 0, 0] %e A357305 3 9 1/2 [1, 0, 0, 1] %e A357305 5 25 2/5 [1, 1, 0, 0, 1] %e A357305 11 121 2/7 [1, 1, 1, 1, 0, 0, 1] %e A357305 45 2025 3/11 [1, 1, 1, 1, 1, 1, 0, 1, 0, 0, 1] %e A357305 181 32761 2/15 [1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 1] %Y A357305 Cf. A000120, A000290, A070939, A159918, A230097. %K A357305 nonn,base,hard,more %O A357305 1,1 %A A357305 _Hugo Pfoertner_, Oct 01 2022 %E A357305 a(7)-a(8) from _Michael S. Branicky_, Oct 01 2022 using A230097, verified with exhaustive search Oct 02 2022 %E A357305 a(9)-a(10) from _Hugo Pfoertner_, Nov 30 2022