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 A091270 #10 Feb 16 2025 08:32:52 %S A091270 0,2,5,13,29,61,125,253,509,1021,2045,4093,8189,16381,32765,65533, %T A091270 131069,262141,524285,1048573,2097149,4194301,8388605,16777213, %U A091270 33554429,67108861,134217725,268435453,536870909,1073741821 %N A091270 Smallest number having in binary representation a prefix of length n that is also a suffix of its successor. %C A091270 A091269(a(n)) = n and A091269(m) < n for m<a(n); %C A091270 a(n) = 2^(n+1) - 3 for n>2, cf. A036563. %H A091270 <a href="/index/Bi#binary">Index entries for sequences related to binary expansion of n</a> %H A091270 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/Binary.html">Binary</a> %H A091270 <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (3,-2). %Y A091270 Cf. A007088. %K A091270 nonn,base %O A091270 0,2 %A A091270 _Reinhard Zumkeller_, Dec 27 2003