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 A087276 #9 Jun 27 2021 07:53:46 %S A087276 1,3,4,7,9,9,11,15,18,19,22,19,22,23,26,31,35,37,41,39,43,45,49,39,43, %T A087276 45,49,47,51,53,57,63,68,71,76,75,80,83,88,79,84,87,92,91,96,99,104, %U A087276 79,84,87,92,91,96,99,104,95,100,103,108,107,112,115 %N A087276 Write n in binary: 1ab..yz, then a(n) = 1ab..yz + ... + 1yz + 1z + 1. %C A087276 a(n) = A087275(n) + n. %F A087276 a(1) = 1, a(2n) = 2a(n) + 1, a(2n+1) = 2*a(n) + floor(log_2(n)) + 2. %o A087276 (PARI) a(n)=local(v, s, l); v=binary(n); l=length(v); s=0; for(k=2, l, s=s+2^(l-k)+sum(m=k+1, l, v[m]*2^(l-m))); s+n %Y A087276 Cf. A005187, A059893, A059894. %K A087276 nonn,easy %O A087276 1,2 %A A087276 _Ralf Stephan_, Aug 27 2003