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A133420 Number of steps to reach 1 under repeated applications of the "5x+1" map of A133419, or -1 if 1 is never reached. 4

%I #13 Jan 15 2021 09:30:39

%S 0,1,1,2,14,2,5,3,2,15,9,3,12,6,15,4,9,3,7,16,6,10,21,4,9,13,3,7,18,

%T 16,16,5,10,10,14,4,19,8,13,17,13,7,7,11,16,22,26,5,16,10,10,14,25,4,

%U 25,8,8,19,23,17,13,17,7,6,17,11,11,11,22,15,26,5,16,20,10,9,20,14,14,18,4,14

%N Number of steps to reach 1 under repeated applications of the "5x+1" map of A133419, or -1 if 1 is never reached.

%C The 5x+1 map sends x to x/2 if x is even, x/3 if x is divisible by 3, otherwise 5x+1.

%H R. J. Mathar, <a href="/A133420/b133420.txt">Table of n, a(n) for n = 1..20000</a>

%H R. J. Mathar, <a href="/A133420/a133420.txt">Maple program to make b-file</a>

%H Tomás Oliveira e Silva, <a href="http://sweet.ua.pt/tos/3x+1.html">The px+1 problem</a>

%H <a href="/index/3#3x1">Index entries for sequences related to 3x+1 (or Collatz) problem</a>

%Y Cf. A133419.

%K nonn,easy

%O 1,4

%A _N. J. A. Sloane_, Nov 27 2007

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Last modified March 4 16:39 EST 2024. Contains 370532 sequences. (Running on oeis4.)