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 A102419 "Dropping time" in 3x+1 problem starting at n (number of steps to reach a lower number than starting value); a(1) = 0 by convention. Also called glide(n). 8
 0, 1, 6, 1, 3, 1, 11, 1, 3, 1, 8, 1, 3, 1, 11, 1, 3, 1, 6, 1, 3, 1, 8, 1, 3, 1, 96, 1, 3, 1, 91, 1, 3, 1, 6, 1, 3, 1, 13, 1, 3, 1, 8, 1, 3, 1, 88, 1, 3, 1, 6, 1, 3, 1, 8, 1, 3, 1, 11, 1, 3, 1, 88, 1, 3, 1, 6, 1, 3, 1, 83, 1, 3, 1, 8, 1, 3, 1, 13, 1, 3, 1, 6, 1, 3, 1, 8, 1, 3, 1, 73, 1, 3, 1, 13, 1, 3, 1, 6 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,3 COMMENTS a(2n) = 1; a(2n+1) = A060445(n). a(n) = A074473(n)-1 for n>1. a(n) = floor(A126241(n)*(1+log(2)/log(3))). [K. Spage, Oct 22 2009] LINKS N. J. A. Sloane, Table of n, a(n) for n = 1..10000 Eric Roosendaal, On the 3x + 1 problem N. J. A. Sloane, First 36 terms of A217934 and A060412 [From Roosendaal web site] EXAMPLE 1: 0 steps 2 1: 1 step 3 10 5 16 8 4 2 1: 6 steps (before it drops below n) 4 2 1: 1 step 5 16 8 4 2 1: 3 steps 6 3 ...: 1 step 7 22 11 34 17 52 26 13 40 20 10 5 ...: 11 steps ... Records: 0.1.6.11.96.132...171... (A217934) at.......1.2.3..7.27.703.10087... (A060412) MATHEMATICA Prepend[Table[Length[NestWhileList[If[EvenQ[#], #/2, 3#+1]&, n, #>=n&]], {n, 2, 99}], 1]-1 (* Jayanta Basu, May 28 2013 *) PROG (Python) def a(n):     if n<3: return n - 1     N=n     x=0     while True:         if n%2==0: n/=2         else: n = 3*n + 1         x+=1         if n

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Last modified December 15 11:43 EST 2019. Contains 329999 sequences. (Running on oeis4.)