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 A122791 #5 Dec 20 2021 18:15:15
%S A122791 3,4,9,2,6,5,1,8,5,2,1,8,6,4,2,4,9,1,2,3,0,5,5,6,0,3,3,7,5,2,9,6,8,0,
%T A122791 6,4,7,4,2,7,2,9,0,5,3,4,8,0,9,0,9,9,9,0,5,3,0,9,1,4,7,4,5,2,2,2,2,3,
%U A122791 3,8,4,4,0,7,2,0,8,2,7,6,0,5,9,1,8,7,0,2,2,8,5,5,1,9,1,0,3,4,6,7,5,4,8,1,4
%N A122791 Decimal expansion of the average "dropping time" of the reduced 3x+1 iteration.
%H A122791 <a href="/index/3#3x1">Index entries for sequences related to 3x+1 (or Collatz) problem</a>
%F A122791 Sum{k>0} k*A100982(k)/2^(A020914(k)-1) = 3.49265185218642491230556033752968...
%Y A122791 Cf. A122458 (dropping time of the reduced Collatz iteration), A100982, A122790.
%K A122791 cons,nonn
%O A122791 1,1
%A A122791 _T. D. Noe_, Sep 11 2006