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 A091473 #18 Jan 04 2023 11:48:51
%S A091473 3,9,2,6,9,9,0,8,1,6,9,8,7,2,4,1,5,4,8,0,7,8,3,0,4,2,2,9,0,9,9,3,7,8,
%T A091473 6,0,5,2,4,6,4,5,4,3,4,1,8,7,2,3,1,5,9,5,9,2,6,8,1,2,2,8,5,1,6,2,0,9,
%U A091473 3,2,4,7,1,3,9,9,3,8,5,4,6,1,7,9,0,1,6,5,1,2,7,4,7,4,5,5,3,6,6,7,8
%N A091473 Integral_{x>=0} (cos(2x) * Product_{n>=1} cos(x/n)) dx.
%C A091473 First differs from Pi/8 (A019675) in the 42nd place.
%H A091473 D. H. Bailey, J. M. Borwein, V. Kapoor and E. Weisstein, <a href="https://www.davidhbailey.com/dhbpapers/tenproblems.pdf">Ten Problems in Experimental Mathematics</a>
%H A091473 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/DefiniteIntegral.html">Definite Integral</a>
%H A091473 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/InfiniteCosineProductIntegral.html">Infinite Cosine Product Integral</a>
%e A091473 0.3926990816987...
%Y A091473 Cf. A091494, A019675, A190573, A221208.
%K A091473 nonn,cons
%O A091473 0,1
%A A091473 _Eric W. Weisstein_, Jan 13 2004