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 A195404 #10 Jul 18 2021 09:56:46 %S A195404 7,2,7,0,9,2,0,6,2,9,2,8,0,7,0,1,2,0,5,2,4,5,5,7,2,3,6,3,8,0,5,8,0,9, %T A195404 4,1,6,2,4,2,4,2,5,2,1,7,4,5,8,0,8,3,2,5,7,3,6,5,7,5,7,6,7,7,6,9,1,4, %U A195404 1,5,2,5,3,8,2,8,6,6,1,4,9,5,9,7,1,7,4,1,8,1,0,0,0,1,3,4,3,4,7,4,5,5,9,6,5 %N A195404 Decimal expansion of shortest length, (B), of segment from side BC through incenter to side BA in right triangle ABC with sidelengths (a,b,c)=(1,sqrt(r),r), where r=(1+sqrt(5))/2 (the golden ratio). %C A195404 See A195284 for definitions and a general discussion. %e A195404 (B)=0.72709206292807012052455723638058094... %t A195404 a = 1; b = Sqrt[c]; c = (1 + Sqrt[5])/2; %t A195404 f = 2 a*b/(a + b + c); %t A195404 x1 = Simplify[f*Sqrt[a^2 + (b + c)^2]/(b + c) ] %t A195404 x2 = Simplify[f*Sqrt[b^2 + (c + a)^2]/(c + a) ] %t A195404 x3 = f*Sqrt[2] %t A195404 N[x1, 100] %t A195404 RealDigits[%] (* (A) A195403 *) %t A195404 N[x2, 100] %t A195404 RealDigits[%] (* (B) A195404 *) %t A195404 N[x3, 100] %t A195404 RealDigits[%] (* (C) A195405 *) %t A195404 N[(x1 + x2 + x3)/(a + b + c), 100] %t A195404 RealDigits[%] (* Philo(ABC,I) A195406 *) %Y A195404 Cf. A195284. %K A195404 nonn,cons %O A195404 0,1 %A A195404 _Clark Kimberling_, Sep 17 2011 %E A195404 a(99) corrected by _Georg Fischer_, Jul 18 2021