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 A085550 #34 Feb 10 2025 11:58:49
%S A085550 3,0,2,7,7,5,6,3,7,7,3,1,9,9,4,6,4,6,5,5,9,6,1,0,6,3,3,7,3,5,2,4,7,9,
%T A085550 7,3,1,2,5,6,4,8,2,8,6,9,2,2,6,2,3,1,0,6,3,5,5,2,2,6,5,2,8,1,1,3,5,8,
%U A085550 3,4,7,4,1,4,6,5,0,5,2,2,2,6,0,2,3,0,9,5,4,1,0,0,9,2,4,5,3,5,8,8,3,6,7,5,7
%N A085550 Decimal expansion of (sqrt(13)-3)/2.
%H A085550 Daniel Starodubtsev, <a href="/A085550/b085550.txt">Table of n, a(n) for n = 0..10000</a>
%H A085550 Cino Hilliard, <a href="http://groups.msn.com/BC2LCC/nreciprocalrecursion.msnw">+ N = Reciprocal Recursion</a> [broken link]
%H A085550 <a href="/index/Al#algebraic_02">Index entries for algebraic numbers, degree 2</a>.
%F A085550 Equals Sum_{k>=1} (-1)^(k-1)/(A006190(k)*A006190(k+1)). - _Vladimir Shevelev_, Feb 23 2013
%F A085550 Tan(arctan(c) + arctan(c^3)) = 1/3. - _Gary W. Adamson_, Apr 02 2024
%e A085550 0.30277563773199464655961...
%t A085550 First[RealDigits[(Sqrt[13] - 3)/2, 10, 100]] (* _Paolo Xausa_, Jun 12 2024 *)
%o A085550 (PARI) (sqrt(13)-3)/2 \\ _Michel Marcus_, Jan 16 2020
%Y A085550 Cf. A010470 (sqrt(13)).
%K A085550 easy,cons,nonn
%O A085550 0,1
%A A085550 _Cino Hilliard_, Jul 04 2003