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A271479 Number of steps for the trajectory of n under the map k -> A271478(k) to reach 1. 3
0, 1, 4, 2, 7, 5, 5, 3, 10, 8, 8, 6, 8, 6, 6, 4, 13, 11, 11, 9, 11, 9, 9, 7, 11, 9, 9, 7, 9, 7, 7, 5, 16, 14, 14, 12, 14, 12, 12, 10, 14, 12, 12, 10, 12, 10, 10, 8, 14, 12, 12, 10, 12, 10, 10, 8, 12, 10, 10, 8, 10, 8, 8, 6, 19, 17, 17, 15, 17, 15, 15, 13, 17, 15, 15, 13, 15, 13 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

COMMENTS

Arises in studying A266569.

Records are 0, 1, 4, 7, 10, 13, 16, 19, 22, 25, 28, 31, 34, 37, 40, ... and occur at positions 1, 2, 3, 5, 9, 17, 33, 65, 129, 257, 513, 1025, 2049, 4097, 8193, ...

LINKS

N. J. A. Sloane, Table of n, a(n) for n = 1..10000

FORMULA

It appears that a(1) = 0, a(n) = 1 + 2*(n mod 2) + a(ceiling(n/2)) for n > 1. - Christian Krause, Apr 28 2019

MAPLE

f:=n->if n mod 2 = 0 then n/2 else 2*n+2; fi; # A271478

a:=[]; B:=1000;

for n from 1 to 100 do

   ct:=0; s:=n;

   for k from 1 to B while s>1 do

   s:=f(s); ct:=ct+1; od:

if ct=B then lprint("error, need to increase limit B"); break; fi;

a:=[op(a), ct]; od:

a;

MATHEMATICA

Table[Length[NestWhileList[If[EvenQ[#], #/2, 2#+2]&, n, #!=1&]]-1, {n, 80}] (* Harvey P. Dale, May 02 2017 *)

CROSSREFS

Cf. A266569, A271478.

Sequence in context: A115302 A109857 A194075 * A259927 A002560 A124908

Adjacent sequences:  A271476 A271477 A271478 * A271480 A271481 A271482

KEYWORD

nonn

AUTHOR

N. J. A. Sloane, Apr 10 2016

STATUS

approved

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Last modified August 9 04:39 EDT 2020. Contains 336319 sequences. (Running on oeis4.)