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Revision History for A000546

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A000546

First occurrence of n consecutive numbers that take same number of steps to reach 1 in 3x+1 problem.
(history; published version)

#14 by T. D. Noe at Wed Jun 20 14:20:41 EDT 2012

STATUS

editing

approved

#13 by T. D. Noe at Wed Jun 20 14:20:32 EDT 2012

LINKS

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

#12 by T. D. Noe at Wed Jun 20 14:20:08 EDT 2012

DATA

1, 12, 28, 314, 98, 386, 943, 1494, 1680, 4722, 6576, 11696, 3982, 2987, 17548, 36208, 7083, 59692, 159116, 79592, 57857, 212160, 352258, 221185, 57346, 294913, 252548, 530052, 331778, 524289, 1088129, 913319, 2065786, 1541308, 1032875, 1264924, 8151894

LINKS

T. D. Noe, <a href="/A000546/b000546.txt">Table of n, a(n) for n = 1..100</a>

MATHEMATICA

Collatz[n_] := Length[NestWhileList[If[EvenQ[#], #/2, 3 # + 1] &, n, # > 1 &]] - 1; nn = 3810; 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 *)

#11 by T. D. Noe at Wed Jun 20 12:41:20 EDT 2012

MATHEMATICA

Collatz[n_] := Length[NestWhileList[If[EvenQ[#], #/2, 3 # + 1] &, n, # > 1 &]] - 1; nn = 38; 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 *)

STATUS

approved

editing

#10 by Russ Cox at Sun Jul 10 18:16:47 EDT 2011

LINKS

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

Discussion

Sun Jul 10

18:16

OEIS Server: https://oeis.org/edit/global/16

#9 by T. D. Noe at Thu Nov 18 23:19:57 EST 2010

STATUS

proposed

approved

#8 by Sean A. Irvine at Thu Nov 18 20:48:18 EST 2010

COMMENTS

Sequence is precise in the sense that n+1 consecutive numbers starting at a(n) do not take the same number of steps.

STATUS

approved

proposed

#7 by N. J. A. Sloane at Thu Nov 11 07:34:06 EST 2010

LINKS

<a href="/Sindx_3.html#3x1">Index entries for sequences related to 3x+1 (or Collatz) problem</a>

KEYWORD

nonn,new

nonn

#6 by N. J. A. Sloane at Fri Feb 27 03:00:00 EST 2009

LINKS

<a href="http://www.research.att.com/~njas/sequences/Sindx_3.html#3x1">Index entries for sequences related to 3x+1 (or Collatz) problem</a>

KEYWORD

nonn,new

nonn

#5 by N. J. A. Sloane at Fri May 16 03:00:00 EDT 2003

LINKS

<a href="http://www.research.att.com/~njas/sequences/Sindx_13.html#3x1">Index entries for sequences related to 3x+1 (or Collatz) problem</a>

KEYWORD

nonn,new

nonn

AUTHOR

Peter L. Stone [ PetStone@(AT)aol.com ]