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 A139347 #20 Feb 07 2022 08:15:51 %S A139347 2,1,1,5,3,8,0,0,7,8,2,4,9,3,2,7,4,6,4,8,5,8,6,2,8,1,1,7,0,3,2,5,8,2, %T A139347 5,5,9,7,8,8,1,2,4,3,6,7,4,6,4,8,2,6,0,8,6,3,7,0,7,5,6,8,9,4,5,9,9,4, %U A139347 5,9,8,7,2,7,5,9,3,2,8,2,0,2,6,8,0,0,3,5,4,7,7,5,6,0,6,9,6,3,4,2,5,8,1,4,5 %N A139347 Decimal expansion of negated tangent of the golden ratio. That is, the decimal expansion of -tan((1+sqrt(5))/2). %C A139347 By the Lindemann-Weierstrass theorem, this constant is transcendental. - _Charles R Greathouse IV_, May 13 2019 %H A139347 <a href="/index/Tra#transcendental">Index entries for transcendental numbers</a>. %F A139347 Equals tan(A001622). %F A139347 From _Amiram Eldar_, Feb 07 2022: (Start) %F A139347 Equals 1/A139348. %F A139347 Equals A139345/A139346. (End) %e A139347 -21.15380078249327464858628117032582559788124367464826... %t A139347 RealDigits[Tan[GoldenRatio], 10, 100][[1]] (* _Amiram Eldar_, Feb 07 2022 *) %o A139347 (PARI) -tan((sqrt(5)+1)/2) \\ _Charles R Greathouse IV_, May 13 2019 %Y A139347 Cf. A001622, A094214, A104457, A098317, A002390, A139339, A139340, A139341, A139342, A139345, A139346, A139348. %K A139347 nonn,cons %O A139347 2,1 %A A139347 _Mohammad K. Azarian_, Apr 15 2008 %E A139347 Offset corrected by _Mohammad K. Azarian_, Dec 13 2008 %E A139347 Sign added to definition by _R. J. Mathar_, Feb 05 2009