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 A247621 #8 Dec 12 2014 19:23:59
%S A247621 0,4,6,1,5,1,4,5,1,3,0,5,9,1,4,2,0,8,8,4,6,5,6,8,3,8,3,5,4,1,7,4,6,7,
%T A247621 4,7,2,8,2,7,4,9,5,5,9,7,4,7,1,0,5,3,7,8,1,4,7,8,9,0,9,7,0,3,8,0,2,8,
%U A247621 3,4,5,1,1,2,4,8,7,9,5,2,0,1,9,8,2,7,0,4,0,5,0,1,1,8,8,9,5,0,1,2,6,8,8,9,7,2
%N A247621 Decimal expansion of Sum_{k>=1} 1/(2*k)-tanh(1/(2*k)).
%H A247621 Philippe Flajolet, Éric Fusy, Xavier Gourdon, Daniel Panario and Nicolas Pouyanne, <a href="http://arxiv.org/abs/math/0606370">A Hybrid of Darboux's Method and Singularity Analysis in Combinatorial Asymptotics</a>, arXiv:math.CO/0606370, p. 18
%e A247621 0.04615145130591420884656838354174674728274955974710537814789097038...
%p A247621 evalf(sum(1/(2*k)-tanh(1/(2*k)), k=1..infinity), 120)
%o A247621 (PARI) default(realprecision,150); sumpos(k=1,(1/(2*k)-tanh(1/(2*k))))
%Y A247621 Cf. A003483.
%K A247621 nonn,cons
%O A247621 0,2
%A A247621 _Vaclav Kotesovec_, Sep 21 2014