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 A139338 #7 May 26 2019 04:37:12
%S A139338 1,2,3,3,4,4,5,6,6,7,7,8,8,9,9,10,11,11,12,12,13,13,14,15,15,16,16,17,
%T A139338 17,18,18,19,20,20,21,21,22,22,23,24,24,25,25,26,26,27,27,28,29,29,30,
%U A139338 30,31,31,32,32,33,34,34,35,35,36,36,37,37,38,39,39,40,40,41,41,42,43
%N A139338 Least k > 0 such that Sum_{i=0..2*n-1} (-k)^i/i! < 0.
%D A139338 Serge Francinou, Herve Gianella and Serge Nicolas, Exercices de mathématiques : oraux X-ENS, Analyse 1, Cassini Editeur, 2003, pp. 119-121.
%F A139338 a(n) = r*n + o(n) where r is the solution to x + log(x) = 0 and 0 < x < 1: r = 0.56714329040978387299996... (see A030178).
%o A139338 (PARI) a(n)=if(n<0,0,k=1;while(sum(i=0,2*n-1,(-k)^i*1./i!)>0,k++);k)
%Y A139338 Cf. A030178.
%K A139338 nonn
%O A139338 1,2
%A A139338 _Benoit Cloitre_, Jun 08 2008