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 A124387 #11 Jan 15 2025 12:07:44 %S A124387 10,11,101,111,1101,10111,101011,1010011,10100011,100111101, %T A124387 1001110111,10011101011,100111000111,1001110001011,10011011110101, %U A124387 100110111100001,1001101110111101,10011011101010011,100110111010011101,1001101110100011111,10011011101000111011 %N A124387 Largest prime < 2*a(n-1) written in binary, a(1)=2. %F A124387 a(n) = A007088(A006992(n)). %t A124387 NestList[FromDigits[IntegerDigits[NextPrime[FromDigits[IntegerDigits[ 2#], 2],-1],2]]&,10,20] (* _Harvey P. Dale_, Sep 26 2015 *) %Y A124387 Cf. A006992, A007088, A126031. %K A124387 nonn %O A124387 1,1 %A A124387 _Artur Jasinski_, Dec 16 2006 %E A124387 Corrected and extended by _Harvey P. Dale_, Sep 26 2015