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 A171782 #8 Sep 01 2020 07:39:26 %S A171782 10,11,100,111,1000,1010,1101,1111,10000,10010,10100,10110,11001, %T A171782 11011,11101,11111,100000,100010,100100,100110,101000,101010,101100, %U A171782 101110,110001,110011,110101,110111,111001,111011,111101,111111,1000000,1000010,1000100,1000110 %N A171782 Binary expansion of numbers in A171781. %H A171782 Amiram Eldar, <a href="/A171782/b171782.txt">Table of n, a(n) for n = 1..10000</a> %F A171782 a(n) = A007088(A171781(n)). - _Amiram Eldar_, Sep 01 2020 %t A171782 bin[n_] := FromDigits[IntegerDigits[n, 2]]; bin /@ Select[Range[2, 70], (d = IntegerDigits[#, 2])[[2]] == d[[-1]] &] (* _Amiram Eldar_, Sep 01 2020 *) %Y A171782 Cf. A007088, A171781. %K A171782 nonn,base %O A171782 1,1 %A A171782 _N. J. A. Sloane_, Oct 12 2010