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 A167877 #7 Mar 15 2014 10:40:05 %S A167877 0,1,0,3,4,3,2,1,0,9,10,9,12,13,12,11,10,9,8,7,6,5,4,3,2,1,0,27,28,27, %T A167877 30,31,30,29,28,27,36,37,36,39,40,39,38,37,36,35,34,33,32,31,30,29,28, %U A167877 27,26,25,24,23,22,21,20,19,18,17,16,15,14,13,12,11,10,9,8,7,6,5,4,3,2 %N A167877 Largest m<=n such that no carry occurs when adding m to n in ternary arithmetic. %C A167877 A167878(n) = a(n) + n. %H A167877 R. Zumkeller, <a href="/A167877/b167877.txt">Table of n, a(n) for n = 0..10000</a> %o A167877 (Haskell) %o A167877 a167877 n = head [x | let ts = a030341_row n, x <- [n, n-1 ..], %o A167877 all (< 3) $ zipWith (+) ts (a030341_row x)] %o A167877 -- _Reinhard Zumkeller_, Mar 15 2014 %Y A167877 Cf. A007089, A167831, A035327 for the decimal and binary cases. %Y A167877 Cf. A030341. %K A167877 base,nonn,look %O A167877 0,4 %A A167877 _Reinhard Zumkeller_, Nov 14 2009