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 A056966 #14 Feb 13 2023 02:58:35
%S A056966 0,0,0,1,0,0,0,1,0,0,0,1,1,1,2,3,0,0,0,1,0,0,0,1,0,0,0,1,1,1,2,3,0,0,
%T A056966 0,1,0,0,0,1,0,0,0,1,1,1,2,3,1,1,2,3,1,1,2,3,2,2,4,5,3,3,6,7,0,0,0,1,
%U A056966 0,0,0,1,0,0,0,1,1,1,2,3,0,0,0,1,0,0,0,1,0,0,0,1,1,1,2,3,0,0,0,1,0,0,0,1,0
%N A056966 In binary: write what is described (putting a leading zero on numbers which have an odd number of binary digits).
%e A056966 a(54)=2 because 54 = 110110 base 2, which can be read as one 1 followed by zero 1's followed by one 0, i.e., 10 base 2 = 2 base 10.
%o A056966 (Python)
%o A056966 def A056966(n):
%o A056966 s = bin(n)[2:]
%o A056966 s = '0'*(len(s)&1)+s
%o A056966 return int('0'+''.join(s[i+1]*int(s[i])for i in range(0,len(s),2)),2) # _Chai Wah Wu_, Feb 12 2023
%Y A056966 Cf. A014081, A049190, A056967.
%K A056966 nonn,base
%O A056966 0,15
%A A056966 _Henry Bottomley_, Jul 20 2000