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 A086318 #19 Feb 16 2025 08:32:50
%S A086318 7,9,1,6,0,3,1,8,3,5,7,7,5,1,1,8,0,7,8,2,3,6,2,8,4,5,5,7,2,3,2,6,8,2,
%T A086318 2,4,0,7,1,7,4,2,4,1,8,0,9,0,7,8,9,4,6,7,3,1,2,3,0,7,8,3,0,9,9,2,2,9,
%U A086318 0,4,4,1,5,0,3,8,9,3,2,9,2,5,5,4,4,6,6,7,9,0,8,6,8,4,0,4,6,3,0,3,8,3
%N A086318 Decimal expansion of asymptotic constant eta for counts of weakly binary trees.
%D A086318 Steven R. Finch, Mathematical Constants, Encyclopedia of Mathematics and its Applications, vol. 94, Cambridge University Press, 2003, Section 5.6, p. 297.
%H A086318 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/WeaklyBinaryTree.html">Weakly binary tree</a>.
%F A086318 Equals lim_{n->oo} A001190(n)*n^(3/2)/A086317^(n-1). - _Vaclav Kotesovec_, Apr 19 2016
%e A086318 0.791603183577511807823628455723268224071742418090789...
%t A086318 digits = 102; c[0] = 2; c[n_] := c[n] = c[n - 1]^2 + 2; eta[n_Integer] := eta[n] = 1/2 * Sqrt[c[n]^2^(-n)/Pi] * Sqrt[3 + Sum[1/Product[c[j], {j, 1, k}], {k, 1, n}]]; eta[5]; eta[n = 10]; While[RealDigits[eta[n], 10, digits] != RealDigits[eta[n - 5], 10, digits], n = n + 5]; RealDigits[eta[n], 10, digits] // First (* _Jean-François Alcover_, May 27 2014 *)
%Y A086318 Cf. A001190, A086317.
%K A086318 nonn,cons
%O A086318 0,1
%A A086318 _Eric W. Weisstein_, Jul 15 2003