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 A000319 #47 Mar 18 2025 01:39:11
%S A000319 1,1,74,-1,-2,-3,0,1,30,-2,-2,29,1,4,-6,0,1,2,-1,-1,-1,-1,-2,-9,0,0,1,
%T A000319 2,-2,-35,-1,-1,-1,-1,-1,-1,-1,-2,-3,0,0,1,5,-2,-2,3,1,1,-4,-1,-1,-1,
%U A000319 -1,-1,-1,-1,-1,-2,-3,1,2,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-2,-3,0,1,2,-1,-2,-21,-7,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0
%N A000319 a(n) = floor(b(n)), where b(n) = tan(b(n-1)), b(0)=1.
%C A000319 Using 3000-digit precision, interval arithmetic provides an efficient method of computing over 2000000 terms of this sequence. The iteration is stopped when an interval contains an integer. So far, no term equals 319. - _T. D. Noe_, Mar 07 2008
%C A000319 The question whether 319 occurs is relevant for sequences A053169 and A053873. - _Antti Karttunen_ and _M. F. Hasler_, Mar 01 2025
%H A000319 T. D. Noe, <a href="/A000319/b000319.txt">Table of n, a(n) for n = 0..10000</a>
%H A000319 Tim Peters, <a href="/A000319/a000319.csv.txt">CSV table of a(n) for n = 0..7366317 in "value,count" format</a>
%e A000319 From _José María Grau Ribas_, Apr 13 2010: (Start)
%e A000319 For n=2, tan(tan(1)) = 74.68... (A085665), so a(2)=74.
%e A000319 For n=3, tan(tan(tan(1))) = -0.8635... (A085666), so a(3)=-1. (End)
%t A000319 Floor[Table[Nest[Tan, 1, n], {n, 1, 200}]] (* _José María Grau Ribas_, Apr 13 2010 *)
%Y A000319 See A381230 (resp. A381231) for when n (resp. -n) appears.
%Y A000319 Cf. A053169, A053873, A085665, A085666.
%Y A000319 Cf. A000329 (with round).
%K A000319 sign
%O A000319 0,3
%A A000319 _N. J. A. Sloane_