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 A145183 #9 Jun 02 2025 00:37:43
%S A145183 9,756,432083484,80668317387203269343374356,
%T A145183 524939187888223206865848253384923777974930416670334526494423558665677185033084
%N A145183 Continued cotangent recurrence a(n+1)=a(n)^3+3*a(n) and a(1)=9.
%C A145183 General formula for continued cotangent recurrences type:
%C A145183 a(n+1)=a(n)3+3*a(n) and a(1)=k is following:
%C A145183 a(n)=Floor[((k+Sqrt[k^2+4])/2)^(3^(n-1))]
%C A145183 For k=1 see A006267
%C A145183 k=2 see A006266
%C A145183 k=3 see A006268
%C A145183 k=4 see A006267(n+1)
%C A145183 k=5 see A006269
%C A145183 k=6 see A145180
%C A145183 k=7 see A145181
%C A145183 k=8 see A145182
%C A145183 k=9 see A145183
%C A145183 k=10 see A145184
%C A145183 k=11 see A145185
%C A145183 k=12 see A145186
%C A145183 k=13 see A145187
%C A145183 k=14 see A145188
%C A145183 k=15 see A145189
%F A145183 a(n+1)=a(n)3+3*a(n) and a(1)=9
%F A145183 a(n)=Floor[((9+Sqrt[9^2+4])/2)^(3^(n-1))]
%t A145183 a = {}; k = 9; Do[AppendTo[a, k]; k = k^3 + 3 k, {n, 1, 6}]; a
%t A145183 or
%t A145183 Table[Floor[((9 + Sqrt[85])/2)^(3^(n - 1))], {n, 1, 5}] (*Artur Jasinski*)
%t A145183 NestList[#^3+3#&,9,5] (* _Harvey P. Dale_, Nov 02 2011 *)
%Y A145183 A006267, A006266, A006268, A006269, A145180, A145181, A145182, A145183, A145184, A145185, A145186, A145187, A145188, A145189
%K A145183 nonn
%O A145183 1,1
%A A145183 _Artur Jasinski_, Oct 03 2008