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 A276994 #36 Sep 27 2016 16:00:37
%S A276994 2,3,0,9,1,3,8,5,9,3,3,3,0,4,9,4,7,3,1,0,9,8,7,2,0,3,0,5,0,1,7,2,1,2,
%T A276994 5,3,1,9,1,1,8,1,4,4,7,2,5,8,1,6,2,8,4,0,1,6,9,4,4,0,2,9,0,0,2,8,4,4,
%U A276994 5,6,4,4,0,7,4,8,3,1,6,8,4,2,7,1,7,2,8,1,6,1,5,7,7,4,4,1,2,1,7,4,3,7,4,6,1
%N A276994 Decimal expansion of the Klarner-Rivest polyomino constant.
%C A276994 Analytic Combinatorics (Flajolet and Sedgewick, 2009, p. 662) has a wrong value of this constant (2.309138593331230...).
%D A276994 Steven R. Finch, Mathematical Constants, Cambridge University Press, 2003, Section 5.19 (Klarner's polyomino constant), p. 380.
%H A276994 E. A. Bender, <a href="http://dx.doi.org/10.1016/0012-365X(74)90134-4">Convex n-ominoes</a>, Discrete Math., 8 (1974), 219-226.
%H A276994 P. Flajolet and R. Sedgewick, <a href="http://algo.inria.fr/flajolet/Publications/books.html">Analytic Combinatorics</a>, 2009, p. 662.
%H A276994 D. A. Klarner and R. L. Rivest, <a href="http://people.csail.mit.edu/rivest/pubs/KR74.pdf">Asymptotic bounds for the number of convex n-ominoes</a>, Discrete Math., 8 (1974), 31-40.
%F A276994 Equals lim n -> infinity A006958(n)^(1/n).
%F A276994 1/A276994 = 0.4330619231293906645846169654189837... is the smallest positive root of the equation Sum_{n>=0} ((-1)^n * z^(n*(n+1)/2) / (Product_{k=1..n} 1-z^k)^2) = 0.
%e A276994 2.309138593330494731098720305017212531911814472581628401694402900284456440748...
%t A276994 1/z/.FindRoot[Sum[(-1)^n * z^(n*(n+1)/2) / QPochhammer[z, z, n]^2, {n, 0, 1000}], {z, 2/5}, WorkingPrecision -> 120]
%Y A276994 Cf. A006958.
%K A276994 nonn,cons
%O A276994 1,1
%A A276994 _Vaclav Kotesovec_, Sep 27 2016