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 A258714 #14 Feb 19 2024 02:08:13
%S A258714 1,3,5,5,6,4,2,7,0,2,8,5,4,8,1,6,7,2,3,3,3,3,2,6,2,7,1,4,5,9,0,7,3,9,
%T A258714 5,5,2,3,3,9,8,8,2,9,3,8,5,9,9,4,8,7,7,2,8,4,6,8,9,7,8,5,8,5,3,3,9,7,
%U A258714 5,0,9,4,9,9,7,7,7,2,1,4
%N A258714 Decimal expansion of Sum_{k>=0} 1/Product_{i=0..k} (2^(2^i) - 1).
%F A258714 From _Amiram Eldar_, Feb 19 2024: (Start)
%F A258714 Equals Sum_{n>=0} 1/A370458(n).
%F A258714 Equals 1/A215016 - 3/2. (End)
%e A258714 1.3556427028548167233332627145907395523398829385994877...
%t A258714 RealDigits[1/NProduct[1 - 1/2^(2^k), {k, 0, Infinity}, WorkingPrecision -> 120] - 3/2][[1]] (* _Amiram Eldar_, Feb 19 2024 *)
%o A258714 (PARI) 1/prodinf(k = 0, 1 - 1/2^(2^k)) - 3/2 \\ _Amiram Eldar_, Feb 19 2024
%Y A258714 Cf. A215016, A258715, A258716, A370458.
%K A258714 nonn,cons
%O A258714 1,2
%A A258714 _N. J. A. Sloane_, Jun 15 2015