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 A319409 #10 Sep 25 2018 02:30:03 %S A319409 0,1,2,2,4,5,5,4,8,9,10,10,10,12,11,8,16,17,18,18,20,21,21,20,20,23, %T A319409 25,24,22,26,23,16,32,33,34,34,36,37,37,36,40,41,42,42,42,44,43,40,40, %U A319409 45,48,46,50,52,51,48,44,51,55,52,46,54,47,32,64,65,66,66,68,69,69,68,72,73,74,74,74,76,75,72,80,81,82,82,84,85,85,84,84,87,89,88,86,90,87,80,80 %N A319409 a(n) = n - A318921(n). %C A319409 How much n decreases by when its binary runs are all shortened by one bit. %H A319409 Rémy Sigrist, <a href="/A319409/b319409.txt">Table of n, a(n) for n = 0..16384</a> %F A319409 a(n) = n iff n is a Fibbinary number (A003714). - _Rémy Sigrist_, Sep 25 2018 %o A319409 (PARI) a(n) = my (p=-1, d=0, b=1, r=n); while (r, my (l=r%2); if (p!=l, p=l, d+=l*b; b*=2); r\=2); n-d \\ _Rémy Sigrist_, Sep 25 2018 %Y A319409 Cf. A003714, A175046, A318921, A319407. %K A319409 nonn,base %O A319409 0,3 %A A319409 _N. J. A. Sloane_, Sep 19 2018