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 A161788 #9 Feb 23 2019 21:52:26 %S A161788 1,1,3,1,1,3,7,1,3,1,1,3,1,7,15,1,1,3,1,1,7,1,1,3,1,1,3,7,1,15,31,1,3, %T A161788 1,7,3,1,1,3,1,1,7,1,1,15,1,1,3,7,1,3,1,1,3,1,7,3,1,1,15,1,31,63,1,1, %U A161788 3,1,1,3,7,1,3,1,1,15,1,7,3,1,1,3,1,1,7,1,1,3,1,1,15,7,1,31,1,1,3,1,7,3,1,1 %N A161788 a(n) is the largest integer of the form 2^k - 1 that divides n. %C A161788 a(n) = 2^A161789(n) - 1. %C A161788 a(A161790(n)) = 1. %p A161788 A161788 := proc(n) for k from ilog2(n+1) to 0 by -1 do if n mod (2^k-1) = 0 then RETURN(2^k-1); fi; od: end: seq(A161788(n),n=1..120) ; # _R. J. Mathar_, Jun 27 2009 %Y A161788 Cf. A000225, A161789, A161790. %K A161788 nonn %O A161788 1,3 %A A161788 _Leroy Quet_, Jun 19 2009 %E A161788 Extended by _R. J. Mathar_, Jun 27 2009