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 A257898 #20 Feb 16 2025 08:33:25
%S A257898 1,1,4,7,7,9,6,8,0,1,3,9,8,7,0,7,5,9,1,1,5,0,7,7,8,8,9,6,7,5,6,7,9,6,
%T A257898 1,9,1,6,6,5,1,8,8,6,8,4,3,2,8,7,6,5,2,3,0,3,2,3,1,4,7,6,5,5,4,6,8,5,
%U A257898 6,2,1,0,6,1,4,7,4,7,0,4,4,8,9,6,5,5,8,2,4,0,2,2,1,2,7,6,5,8,9,3,1,6,1,7,7,5,5,8,5
%N A257898 Decimal expansion of Sum_{n=2..infinity} (-1)^n/log(log(n)), negated.
%C A257898 A very slowly convergent series, converging in virtue of Leibniz's rule.
%H A257898 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/LeibnizCriterion.html">Leibniz Criterion</a>
%H A257898 Wikipedia, <a href="http://en.wikipedia.org/wiki/Alternating_series_test">Alternating series test</a>
%e A257898 -11.47796801398707591150778896756796191665188684328765...
%p A257898 evalf(sum((-1)^n/log(log(n)), n = 2..infinity), 120);
%t A257898 NSum[(-1)^n/Log[Log[n]], {n, 2, Infinity}, AccuracyGoal -> 120, Method -> "AlternatingSigns", WorkingPrecision -> 200]
%o A257898 (PARI) default(realprecision, 120); sumalt(n=2, (-1)^n/log(log(n)))
%Y A257898 Cf. A099769, A257837, A257812.
%K A257898 nonn,cons
%O A257898 2,3
%A A257898 _Iaroslav V. Blagouchine_, May 12 2015