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 A167831 #7 Mar 15 2014 10:39:54 %S A167831 0,1,2,3,4,4,3,2,1,0,10,11,12,13,14,14,13,12,11,10,20,21,22,23,24,24, %T A167831 23,22,21,20,30,31,32,33,34,34,33,32,31,30,40,41,42,43,44,44,43,42,41, %U A167831 40,49,48,47,46,45,44,43,42,41,40,39,38,37,36,35,34,33,32,31,30,29,28,27 %N A167831 Largest m<=n such that no carry occurs when adding m to n in decimal arithmetic. %C A167831 A167832(n) = a(n) + n. %H A167831 R. Zumkeller, <a href="/A167831/b167831.txt">Table of n, a(n) for n = 0..9999</a> %o A167831 (Haskell) %o A167831 a167831 n = head [x | let ds = a031298_row n, x <- [n, n-1 ..], %o A167831 all (< 10) $ zipWith (+) ds (a031298_row x)] %o A167831 -- _Reinhard Zumkeller_, Mar 15 2014 %Y A167831 Cf. A167877, A035327 for the ternary and binary cases. %Y A167831 Cf. A031298. %K A167831 base,nonn,look %O A167831 0,3 %A A167831 _Reinhard Zumkeller_, Nov 14 2009