

A193688


Number of steps to reach 1 in Collatz (3x+1) problem starting with 2^n  1.


4



0, 7, 16, 17, 106, 107, 46, 47, 61, 62, 156, 157, 158, 159, 129, 130, 224, 225, 177, 178, 303, 304, 473, 474, 444, 445, 384, 385, 448, 449, 450, 451, 527, 528, 529, 530, 531, 532, 533, 534, 535, 536, 586, 587, 588, 589, 590, 591, 592, 593, 594, 595, 852
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OFFSET

1,2


LINKS

Arkadiusz Wesolowski, Table of n, a(n) for n = 1..10000
Index entries for sequences related to 3x+1 (or Collatz) problem
Eric Weisstein's World of Mathematics, Collatz Problem


FORMULA

For larger n, a(n) ~ 13.5*n.


MATHEMATICA

Table[Length[NestWhileList[If[OddQ@#, 3 # + 1, #/2] &, 2^n  1, # > 1 &]]  1, {n, 60}] (* Arkadiusz Wesolowski, Sep 16 2011 *)


CROSSREFS

Cf. A006577, A179118 (starting with 2^n+1).
Sequence in context: A070417 A101681 A067776 * A132348 A177763 A101073
Adjacent sequences: A193685 A193686 A193687 * A193689 A193690 A193691


KEYWORD

nonn


AUTHOR

Arkadiusz Wesolowski, Aug 02 2011


STATUS

approved



