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 A036839 #49 Feb 16 2025 08:32:37
%S A036839 0,2,4,6,8,1,12,14,16,18,11,22,33,44,55,66,77,88,99,11,22,33,44,55,66,
%T A036839 77,88,99,11,112,33,44,55,66,77,88,99,11,112,123,44,55,66,77,88,99,11,
%U A036839 112,123,134,55,66,77,88,99,11,112,123,134,145,66,77
%N A036839 RATS(n): Reverse Add Then Sort the digits.
%C A036839 a(n) = RATS(n), not RATS(a(n-1)).
%C A036839 Row 10 of A288535. - _Andrey Zabolotskiy_, Jun 14 2017
%H A036839 Indranil Ghosh, <a href="/A036839/b036839.txt">Table of n, a(n) for n = 0..50000</a> (terms 0..1000 from T. D. Noe)
%H A036839 R. K. Guy, <a href="http://www.jstor.org/stable/2325149">Conway's RATS and other reversals</a>, Unsolved Problems Column, American Math. Monthly, Vol. 96, pp. 425-428, May 1989.
%H A036839 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/RATSSequence.html">RATS Sequence</a>
%F A036839 Form m by Reversing the digits of n, Add m to n Then Sort the digits of the sum into increasing order to get a(n).
%F A036839 a(n) = A004185(A056964(n)). [_Reinhard Zumkeller_, Mar 14 2012]
%e A036839 1 -> 1 + 1 = 2, so a(1) = 2; 3 -> 3 + 3 = 6, so a(3) = 6.
%p A036839 read transforms; RATS := n -> digsort(n + digrev(n));
%t A036839 FromDigits[Sort[IntegerDigits[#+FromDigits[Reverse [IntegerDigits[#]]]]]] & /@Range[0,80] (* _Harvey P. Dale_, Mar 26 2011 *)
%o A036839 (Haskell)
%o A036839 a036839 = a004185 . a056964 -- _Reinhard Zumkeller_, Mar 14 2012
%o A036839 (Python)
%o A036839 def A036839(n):
%o A036839 x = str(n+int(str(n)[::-1]))
%o A036839 return int("".join(sorted(x))) # _Indranil Ghosh_, Jan 28 2017
%Y A036839 Cf. A004000, A004185, A288535.
%Y A036839 Cf. A161593, A114611, A009994, A004086.
%K A036839 nonn,base,nice,easy,look
%O A036839 0,2
%A A036839 _N. J. A. Sloane_, Jan 19 2002