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 A229686 #9 Sep 30 2013 12:57:41 %S A229686 -1,-2,-4,-9,-29,-85,-311,-1549,-9851,-74587,-956633 %N A229686 The negative number of minimum absolute value not obtainable from 1 in n steps using addition, multiplication, and subtraction. %C A229686 This is similar to A141414 but applied to negative numbers. It is the greatest negative number that requires an n step SLP (Stright Line Program) to compute it. %e A229686 For n=1 the value is -1 since -1 requires 2 steps SLP: 1,2,-1. %e A229686 For n=2 the value is -2 since -2 requires 3 steps SLP: 1,2,3,-2. %e A229686 For n=3 the value is -4 since -3 also requires only 3 steps but -4 requires 4: 1,2,4,5,-4. %Y A229686 Cf. A141414, A216999, A214872. %K A229686 sign,hard %O A229686 0,2 %A A229686 _Gil Dogon_, Sep 27 2013