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 A323417 #36 Oct 20 2019 06:05:12
%S A323417 3,2,1,6,3,2
%N A323417 When a prime-based mapping reaches 0.
%C A323417 Writing p_i for the i-th prime, A000040(i); let n_0 = n, and apply the mapping n_i = n_{i-1} + p_i (if p_i > n_{i-1}) else n_{i-1} - p_i. Then a(n) is the least k > 0 for which n_k = 0, or -1 if no such k exists.
%C A323417 In the traversal of n_i for a given n, if it reaches a local minimum after subtracting p_i, it will next reach a local minimum at p_j which will be close to 3p_i.
%C A323417 Conjecture: a(n) > 0 for all n.
%C A323417 For n in { 6 16 20 30 42 50 51 56 70 76 84 85 90 92 }, a(n) is unknown; in each case either a(n) = -1 or a(n) > 2 * 10^12. a(n) is known for all other n <= 100: see the A-file for details.
%H A323417 Nicholas Matteo, <a href="/A323417/a323417_1.txt">Known values for n in 0 .. 1000</a>
%Y A323417 A309222 is the trajectory of this mapping with n_0 = 6.
%K A323417 nonn,more
%O A323417 0,1
%A A323417 _Hugo van der Sanden_, Aug 30 2019