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 A122143 #9 Nov 09 2019 09:18:36
%S A122143 3,2,4,1,3,7,7,4,0,0,5,3,3,2,9,8,1,7,2,4,1,0,9,3,4,7,5,0,0,6,2,7,3,7,
%T A122143 4,7,1,2,0,3,6,5,2,0,1,5,1,9,2,4,5,5,2,7,2,4,8,0,8,5,9,3,3,2,1,6,0,9,
%U A122143 9,2,6,7,2,6,0,0,9,6,3,7,4,5,1,9,6,1,1,4,8,7,9,4,8,7,0,0,1,7,1,3,1,2,9,3
%N A122143 Decimal expansion of Sum_{k >= 1} cos(k)/k^2.
%C A122143 Also, decimal expansion of the real part of Sum_{k>=1} e^(i*k)/k^2. [_Bruno Berselli_, Mar 24 2013]
%F A122143 Equals (2*Pi*(Pi-3)+3)/12.
%e A122143 0.324137740053329817241093475006273747120365201519245527248085933216...
%t A122143 Print[x=FullSimplify[Sum[Cos[n]/n^2, {n,Infinity}]]]; RealDigits[N[x,110]][[1]]
%o A122143 (PARI) (2*Pi*(Pi-3)+3)/12 \\ _Jianing Song_, Nov 09 2019
%Y A122143 Cf. A096418 (decimal expansion of Sum_{k >= 1} sin(k)/k^2).
%Y A122143 Cf. A263192, A121225.
%K A122143 nonn,cons
%O A122143 0,1
%A A122143 _T. D. Noe_, Aug 28 2006