cp's OEIS Frontend

A332209 Starting from sigma(n), number of halving and tripling steps to reach 1 in '3x+1' problem, or -1 if 1 is never reached.

%I A332209 #9 Feb 16 2020 17:35:47
%S A332209 0,7,2,16,8,9,3,17,9,20,9,18,17,10,10,106,20,34,7,8,5,21,10,19,106,8,
%T A332209 8,19,18,22,5,107,11,112,11,92,21,19,19,17,8,12,16,9,35,22,11,108,32,
%U A332209 17,22,25,112,20,22,20,9,17,19,10,107,12,12,46,9,23,14,108,12,23,22,119,22,33,108,15,12,10,9,18,95,108,9,21,113,28,20,18,17
%N A332209 Starting from sigma(n), number of halving and tripling steps to reach 1 in '3x+1' problem, or -1 if 1 is never reached.
%H A332209 Antti Karttunen, <a href="/A332209/b332209.txt">Table of n, a(n) for n = 1..8192</a>
%H A332209 Antti Karttunen, <a href="/A332209/a332209.txt">Data supplement: n, a(n) computed for n = 1..65537</a>
%H A332209 <a href="/index/3#3x1">Index entries for sequences related to 3x+1 (or Collatz) problem</a>
%H A332209 <a href="/index/Si#SIGMAN">Index entries for sequences related to sigma(n)</a>
%F A332209 a(n) = A006577(A000203(n)).
%F A332209 a(n) = A332452(n) + A332453(n).
%o A332209 (PARI)
%o A332209 A006577(n) = if(n<0, 0, s=n; c=0; while(s>1, s=if(s%2, 3*s+1, s/2); c++); c); \\ From A006577
%o A332209 A332209(n) = A006577(sigma(n));
%Y A332209 Cf. A000203, A006577, A332452, A332453.
%K A332209 nonn
%O A332209 1,2
%A A332209 _Antti Karttunen_, Feb 16 2020