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%I #14 Jun 20 2012 14:20:41
%S 1,12,28,314,98,386,943,1494,1680,4722,6576,11696,3982,2987,17548,
%T 36208,7083,59692,159116,79592,57857,212160,352258,221185,57346,
%U 294913,252548,530052,331778,524289,1088129,913319,2065786,1541308,1032875,1264924,8151894
%N First occurrence of n consecutive numbers that take same number of steps to reach 1 in 3x+1 problem.
%C Sequence is precise in the sense that n+1 consecutive numbers starting at a(n) do not take the same number of steps.
%H T. D. Noe, <a href="/A000546/b000546.txt">Table of n, a(n) for n = 1..100</a>
%H <a href="/index/3#3x1">Index entries for sequences related to 3x+1 (or Collatz) problem</a>
%t Collatz[n_] := Length[NestWhileList[If[EvenQ[#], #/2, 3 # + 1] &, n, # > 1 &]] - 1; nn = 10; t = Table[0, {nn}]; t[[1]] = 1; rep = 1; last = 0; n = 1; While[Times @@ t == 0, n++; r = Collatz[n]; If[r == last, rep++, If[0 < rep <= nn && t[[rep]] == 0, t[[rep]] = n - rep]; last = r; rep = 1]]; t (* _T. D. Noe_, Jun 20 2012 *)
%Y Cf. A000547.
%K nonn
%O 1,2
%A Peter L. Stone [ PetStone(AT)aol.com ]
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