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 A097283 #2 Mar 30 2012 18:57:05 %S A097283 1,2,1,3,1,4,2,3,1,5,2,4,1,6,2,5,3,4,1,7,2,6,3,5,1,8,2,7,3,6,4,5,1,9, %T A097283 2,8,3,7,4,6,1,10,2,9,3,8,4,7,5,6,1,11,2,10,3,9,4,8,5,7,1,12,2,11,3, %U A097283 10,4,9,5,8,6,7,1,13,2,12,3,11,4,10,5,9,6,8,1,14,2,13,3,12,4,11,5,10,6,9,7,8 %N A097283 Contains exactly once every pair (i,j) satisfying 0 < i < j. %C A097283 All pairs (i,j) having i > j occur except those of the form (i,i-1) for i>=3. (Those are included at A097285.) %e A097283 Terms are lexically ordered in pairs by sum: %e A097283 1 2 (sum = 3) %e A097283 1 3 (sum = 4) %e A097283 1 4 2 3 (two pairs having sum = 5), etc. %Y A097283 Cf. A097284, A097285. %K A097283 nonn %O A097283 1,2 %A A097283 _Clark Kimberling_, Aug 05 2004