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 A331985 #10 Feb 05 2020 08:58:54 %S A331985 1,2,2,4,2,2,4,8,2,2,2,12,4,5,8,16,2,2,2,4,2,2,12,24,4,4,5,6,8,10,16, %T A331985 32,2,2,2,4,2,2,4,40,2,2,2,9,12,16,24,48,4,4,4,4,5,5,6,56,8,9,10,12, %U A331985 16,21,32,64,2,2,2,4,2,2,4,8,2,2,2,16,4,26,40 %N A331985 a(n) is the least positive k such that n AND floor(n/k) = 0 (where AND denotes the bitwise AND operator). %C A331985 This sequence has similarities with A261891; here we divide and round down, there we multiply, in order to obtain a number with no common bit with the original. %H A331985 Rémy Sigrist, <a href="/A331985/b331985.txt">Table of n, a(n) for n = 0..8192</a> %F A331985 a(n) = 2 iff n is a positive Fibbinary number (A003714). %e A331985 For n = 3: %e A331985 - 3 AND floor(3/1) = 3, %e A331985 - 3 AND floor(3/2) = 1, %e A331985 - 3 AND floor(3/3) = 1, %e A331985 - 3 AND floor(3/4) = 0, %e A331985 - hence a(3) = 4. %o A331985 (PARI) a(n) = for (k=1, oo, if (bitand(n,n\k)==0, return (k))) %Y A331985 Cf. A003714, A261891, A332011. %K A331985 nonn,base %O A331985 0,2 %A A331985 _Rémy Sigrist_, Feb 03 2020