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 A267193 #11 Jan 24 2016 19:43:55 %S A267193 9,8,7,6,5,4,3,2,1,0,98,88,78,68,58,48,38,28,18,8,97,87,77,67,57,47, %T A267193 37,27,17,7,96,86,76,66,56,46,36,26,16,6,95,85,75,65,55,45,35,25,15,5, %U A267193 94,84,74,64,54,44,34,24,14,4,93,83,73,63,53,43,33,23,13 %N A267193 Complement obverse of n. %C A267193 Replace digits of n by their 9's complements, reverse the order, omit any leading zeros. %C A267193 Suggested by a posting by Mike Stay to the Math Fun Mailing List, Jan 24 2016, which in turn was loosely based on the definition used in logic (see the Philosophy Pages link). %H A267193 Alois P. Heinz, <a href="/A267193/b267193.txt">Table of n, a(n) for n = 0..9999</a> %H A267193 Garth Kemerling, <a href="http://www.philosophypages.com/lg/e07b.htm">Philosophy Pages: Immediate Inferences</a>. %e A267193 The 9's complement of the digits of 980 are 019, so a(980) = 910. %p A267193 a:= n-> (s-> parse(cat(seq(9-s[i], i=1..nops(s)))) %p A267193 )(convert(n, base, 10)): %p A267193 seq(a(n), n=0..100); # _Alois P. Heinz_, Jan 24 2016 %Y A267193 Cf. A061601 (9's complement of n). %K A267193 nonn,base %O A267193 0,1 %A A267193 _N. J. A. Sloane_, Jan 24 2016 %E A267193 More terms from _Alois P. Heinz_, Jan 24 2016