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 A330862 #13 Apr 28 2020 17:08:22
%S A330862 1,2,1,0,7,2,4,1,3,0,3,0,1,0,5,9,1,8,0,1,3,6,1,7,2,8,5,6,1,0,5,9,0,5,
%T A330862 0,4,6,3,6,8,0,4,1,6,3,1,1,2,3,1,3,7,6,4,3,4,7,6,1,5,9,2,4,5,5,4,0,0,
%U A330862 0,6,8,7,5,6,5,9,1,8,4,5,0,4,9,9,1,6,5,0,7,6,1,0,1,3,3,5,5,5,3,9,5,3,9,9,6,4,6,3,3,0,9
%N A330862 Decimal expansion of Product_{k>=1} (1 - 1/(-2)^k).
%F A330862 Equals Product_{k>=1} (4^k - 1)*(4^k + 2)/4^(2*k).
%F A330862 Equals exp(-Sum_{k>=1} A000203(k)/(k*(-2)^k)).
%e A330862 (1 + 1/2) * (1 - 1/2^2) * (1 + 1/2^3) * (1 - 1/2^4) * (1 + 1/2^5) * ... = 1.2107241303010591801361728561...
%t A330862 RealDigits[QPochhammer[-1/2, -1/2], 10, 111] [[1]]
%t A330862 N[QPochhammer[-2, 1/4]*QPochhammer[1/4]/3, 120] (* _Vaclav Kotesovec_, Apr 28 2020 *)
%o A330862 (PARI) prodinf(k=1, 1 - 1/(-2)^k) \\ _Michel Marcus_, Apr 28 2020
%Y A330862 Cf. A000203, A048651, A065446, A079555, A081845, A085011, A100221, A132020, A330863.
%K A330862 nonn,cons
%O A330862 1,2
%A A330862 _Ilya Gutkovskiy_, Apr 28 2020