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 A081431 #17 Jan 30 2023 12:29:05
%S A081431 0,1,1,3,1,5,3,7,1,9,1,13,21,31,37,51,47,113,69,109,1,3,13,1,21,11,31,
%T A081431 9,37,29,3,11,29,33,53,43,63,73,101,93,1,7,3,17,13,27,1,41,21,61,5,15,
%U A081431 19,49,45,59,65,105,85,125,3,1,11,9,29,7,33,25,53,3,7,17,27,41
%N A081431 RevBinary(RevDecimal(n)), where RevBinary(m) is the binary reversal of m (A030101) and RevDecimal(m) is the decimal reversal of m (A004086).
%H A081431 Harvey P. Dale, <a href="/A081431/b081431.txt">Table of n, a(n) for n = 0..1000</a>
%F A081431 a(n) = A030101(A004086(n)). - _Michel Marcus_, Jan 30 2023
%t A081431 Table[IntegerReverse[IntegerReverse[n],2],{n,0,80}] (* Requires Mathematica version 10 or later *) (* _Harvey P. Dale_, Dec 03 2018 *)
%o A081431 (Python)
%o A081431 def a(n): return int(bin(int(str(n)[::-1]))[:1:-1], 2)
%o A081431 print([a(n) for n in range(74)]) # _Michael S. Branicky_, Jan 30 2023
%o A081431 (PARI) a(n) = fromdigits(Vecrev(binary(fromdigits(Vecrev(digits(n))))), 2); \\ _Michel Marcus_, Jan 30 2023
%Y A081431 Cf. A004086, A030101.
%Y A081431 Cf. A081432, A081433, A007088.
%K A081431 nonn,base
%O A081431 0,4
%A A081431 _Reinhard Zumkeller_, Mar 20 2003