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 A244645 #21 Feb 08 2023 16:22:48
%S A244645 1,2,7,7,4,0,9,0,5,7,5,5,9,6,3,6,7,3,1,1,9,4,9,5,3,4,9,2,1,0,2,4,3,3,
%T A244645 2,1,1,5,5,6,6,3,4,4,8,0,3,9,0,2,4,7,2,3,2,6,9,3,4,9,1,9,8,4,0,7,5,1,
%U A244645 5,1,5,1,5,1,9,5,5,4,5,1,9,6,0,7,6,2,4,3,0,6,3,1,6,3,3,1,4,1,0,8,8,0,5,0,3
%N A244645 Decimal expansion of the sum of the reciprocals of the octagonal numbers (A000567).
%H A244645 Lawrence Downey, Boon W. Ong, and James A. Sellers, <a href="https://www.d.umn.edu/~jsellers/downey_ong_sellers_cmj_preprint.pdf">Beyond the Basel Problem: Sums of Reciprocals of Figurate Numbers</a>, Coll. Math. J., 39, no. 5 (2008), 391-394.
%H A244645 Wikipedia, <a href="http://en.wikipedia.org/wiki/Polygonal_number">Polygonal number</a>
%F A244645 Equals Sum_{n>=1} 1/(3*n^2 - 2*n).
%F A244645 Equals Pi/(4*sqrt(3)) + 3*log(3)/4. - _Vaclav Kotesovec_, Jul 05 2014
%e A244645 1.2774090575596367311949534921024332115566344803902472326934919840751515151955452...
%t A244645 RealDigits[ Sum[1/(3n^2 - 2n), {n, 1 , Infinity}], 10, 111][[1]]
%o A244645 (PARI) sumpos(n=1, 1/(3*n^2 - 2*n)) \\ _Michel Marcus_, Sep 12 2016
%o A244645 (PARI) sumnumrat(1/(3*n-2)/n,1) \\ _Charles R Greathouse IV_, Feb 08 2023
%Y A244645 Cf. A000038, A013661, A244639, A244644, A244646, A244647, A244648, A244649, A000567.
%K A244645 nonn,cons,easy
%O A244645 1,2
%A A244645 _Robert G. Wilson v_, Jul 03 2014