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 A247553 #5 Sep 19 2014 09:40:14 %S A247553 3,9,4,3,8,4,7,6,8,8,3,6,8,1,3,6,2,8,2,5,4,0,3,9,2,1,8,5,4,3,1,9,9,6, %T A247553 8,1,6,0,7,9,5,3,9,9,0,3,8,9,3,7,5,1,5,2,2,2,8,8,3,7,3,7,9,0,9,4,0,1, %U A247553 2,9,3,4,2,3,1,5,0,8,8,0,0,2,0,7,9,1,6,1,8,3,7,7,2,8,8,4,8,0,7,6,6,7 %N A247553 Decimal expansion of A(rectangles), an analog of Moser's worm constant, which is associated with the class of rectangular regions of the plane. %D A247553 Steven R. Finch, Mathematical Constants, Cambridge University Press, 2003, Section 8.4 Moser's Worm Constant, p. 492. %F A247553 A = beta*sqrt(1 - beta^2), where beta is A240969. %e A247553 0.39438476883681362825403921854319968160795399... %t A247553 phi = ArcSin[1/6 + (4/3)*Sin[(1/3)*ArcSin[17/64]]]; psi = ArcTan[(1/2)*Sec[phi]]; beta = (1/2)*(Pi/2 - phi - 2*psi + Tan[phi] + Tan[psi])^(-1); A = beta*Sqrt[1 - beta^2]; RealDigits[A, 10, 102] // First %Y A247553 Cf. A240969 (beta). %K A247553 nonn,cons %O A247553 0,1 %A A247553 _Jean-François Alcover_, Sep 19 2014