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 A140900 #18 Mar 05 2024 07:10:52
%S A140900 0,2,4,8,10,12,16,18,24,32,34,36,38,40,42,48,52,56,64,66,68,70,80,82,
%T A140900 96,100,112,128,130,132,134,136,138,140,142,144,146,148,150,160,162,
%U A140900 168,170,176,178,192,196,200,204,208,212,224,232,240,256,258,260,262,264
%N A140900 A nonnegative integer n is included if the binary representation of n and the digit-reversal (with leading 0's) of the binary representation of n do not have any 1's in the same position.
%C A140900 All terms of this sequence are even.
%C A140900 Number of terms less than or equal to 10^n: 1, 5, 26, 162, 1045, 5976, 38980, 249229, 1416583, 9381238, ..., . - _Robert G. Wilson v_, Aug 04 2008
%C A140900 Number of terms < 2^k: 1, 2, 3, 6, 18, 27, 54, 81,... (A038754). - _T. D. Noe_, Apr 09 2009
%H A140900 T. D. Noe, <a href="/A140900/b140900.txt">Table of n, a(n) for n=1..1000</a>
%e A140900 36 in binary is 100100. The digit-reversal (with leading 0's) of this is 001001. These binary representations have no 1's in the same location (i.e., they can be added in binary without any carries). So 36 is in this sequence.
%t A140900 fQ[n_] := Block[{id = IntegerDigits[n, 2]}, Max@ Union[id + Reverse@ id] < 2]; Select[2 Range[0, 134], fQ@# &] (* _Robert G. Wilson v_, Aug 04 2008 *)
%o A140900 (PARI) is(n) = my (b=if (n, binary(n), [0])); vecmax(b+Vecrev(b))<=1 \\ _Rémy Sigrist_, Jun 11 2022
%Y A140900 A035928 is a subsequence.
%K A140900 base,nonn
%O A140900 1,2
%A A140900 _Leroy Quet_, Jul 24 2008
%E A140900 More terms from _Robert G. Wilson v_, Aug 04 2008