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 A274687 #25 Nov 23 2019 04:08:30 %S A274687 1,-1,2,-3,4,-4,5,-6,6,-7,8,-9,10,-10,11,-12,13,-14,14,-15,16,-16,17, %T A274687 -18,18,-19,20,-21,22,-22,23,-24,24,-25,26,-26,27,-28,29,-30,30,-31, %U A274687 32,-33,34,-34,35,-36,37,-38,38,-39,40,-40,41,-42,42,-43,44,-45,46 %N A274687 Sequence and first differences (A274688) together list every integer except zero exactly once. %C A274687 This is the lexicographically earliest sequence that together with its first differences (A274688) contains every integer except 0 exactly once. %C A274687 Each term is chosen so that |a(n)| is minimal such that neither a(n) nor (a(n) - a(n-1)) has occurred previously in either this sequence or this sequence's first differences. %e A274687 a(1) = 1; the next number with the lowest possible absolute value that has not occurred yet is -1. -1 - (1) = -2, which also has not yet occurred, so a(2) = -1. The next available term is 2. 2 - (-1) = 3, which is also available, so a(3) = 2. %Y A274687 Cf. A005228, A274688. %K A274687 sign %O A274687 1,3 %A A274687 _Max Barrentine_, Jul 02 2016