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 A139348 #23 Feb 07 2022 02:59:56
%S A139348 0,4,7,2,7,2,8,2,8,6,6,4,7,9,4,4,8,1,1,8,9,3,5,6,5,0,9,6,0,6,2,1,6,3,
%T A139348 3,4,2,0,0,5,6,1,0,5,7,2,2,5,5,6,5,3,3,0,9,7,7,2,9,9,2,5,3,2,4,7,9,8,
%U A139348 7,7,2,2,1,4,5,2,5,6,8,8,1,6,8,7,9,8,8,7,5,0,5,2,9,9,3,8,8,0,7,0,2,1,5,3
%N A139348 Decimal expansion of negated cotangent of the golden ratio. That is, the decimal expansion of -cot((1+sqrt(5))/2).
%C A139348 By the Lindemann-Weierstrass theorem, this constant is transcendental. - _Charles R Greathouse IV_, May 13 2019
%H A139348 <a href="/index/Tra#transcendental">Index entries for transcendental numbers</a>.
%F A139348 Equals cot(A001622).
%F A139348 From _Amiram Eldar_, Feb 07 2022: (Start)
%F A139348 Equals 1/A139347.
%F A139348 Equals A139346/A139345. (End)
%e A139348 0.04727282866479448118935650960621633420056105722556...
%t A139348 Join[{0},RealDigits[-Cot[GoldenRatio],10,120][[1]]] (* _Harvey P. Dale_, Sep 18 2013 *)
%o A139348 (PARI) -cotan((sqrt(5)+1)/2) \\ _Charles R Greathouse IV_, May 13 2019
%Y A139348 Cf. A001622, A094214, A104457, A098317, A002390, A139339, A139340, A139341, A139342, A139345, A139346, A139347.
%K A139348 nonn,cons
%O A139348 0,2
%A A139348 _Mohammad K. Azarian_, Apr 15 2008
%E A139348 Added sign in definition. Leading zero dropped by _R. J. Mathar_, Feb 05 2009