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 A207528 #43 Feb 16 2025 08:33:16
%S A207528 0,0,5,2,4,0,7,0,4,6,7,7,7,0,4,7,7,1,1,4,8,5,6,8,9,2,0,0,7,0,1,0,5,8,
%T A207528 9,3,7,5,8,6,8,4,3,4,4,5,5,0,8,3,4,9,2,8,6,8,4,7,6,0,3,3,3,5,5,7,9,2,
%U A207528 0,8,6,4,4,5,2,4,5,4,8,0,3,5,1,7,4,6,6,3,2,7,7,0,3,5,3,0,8
%N A207528 Decimal expansion of 4th du Bois-Reymond constant.
%D A207528 Steven R. Finch, Mathematical Constants, Cambridge, 2003, pp. 237-239.
%H A207528 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/duBois-ReymondConstants.html">du Bois-Reymond Constants</a>.
%F A207528 2*Sum_{k>=1} (1 + (x_k)^2)^(-2) = (e^4 - 4*e^2 - 25)/8, where x_k is the k-th root of t = tan t and e = 2.71828... is the natural logarithm base.
%e A207528 0.0052407046777047711...
%t A207528 RealDigits[(E^4 - 4E^2 - 25)/8, 10, 100][[1]]
%Y A207528 Cf. A138730 (continued fraction expansion).
%Y A207528 Cf. A062546 (c2), A224196 (c3), A243108 (c5), A245333 (c6).
%K A207528 nonn,cons
%O A207528 0,3
%A A207528 _Alonso del Arte_, Feb 24 2012