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A166549 The number of halving steps of the Collatz 3x+1 map to reach 1 starting from 2n-1. 2
0, 5, 4, 11, 13, 10, 7, 12, 9, 14, 6, 11, 16, 70, 13, 67, 18, 10, 15, 23, 69, 20, 12, 66, 17, 17, 9, 71, 22, 22, 14, 68, 19, 19, 11, 65, 73, 11, 16, 24, 16, 70, 8, 21, 21, 59, 13, 67, 75, 18, 18, 56, 26, 64, 72, 45, 10, 23, 15, 23, 61, 31, 69, 31, 77, 20, 20, 28, 58, 28, 12, 66, 74, 74, 17 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Table of n, a(n) for n=1..75.

Index to sequences related to the 3x+1 problem

FORMULA

a(n) = A006577(2n-1) - A075680(n).

MAPLE

A006370 := proc(n) if type(n, 'even') then n/2; else 3*n+1 ; end if; end proc:

A006577 := proc(n) a := 0 ; x := n ; while x > 1 do x := A006370(x) ; a := a+1 ; end do; a ; end proc:

A006667 := proc(n) a := 0 ; x := n ; while x > 1 do if type(x, 'even') then x := x/2 ; else x := 3*x+1 ; a := a+1 ; end if; end do; a ; end proc:

A075680 := proc(n) A006667(2*n-1) ; end proc:

A166549 := proc(n) A006577(2*n-1)-A075680(n) ; end: seq(A166549(n), n=1..120) ; # R. J. Mathar, Oct 18 2009

CROSSREFS

Cf. A006577, A075680.

Sequence in context: A330614 A051552 A165367 * A324781 A232894 A262902

Adjacent sequences:  A166546 A166547 A166548 * A166550 A166551 A166552

KEYWORD

nonn

AUTHOR

Jimin Park, Oct 16 2009

EXTENSIONS

Edited and extended by R. J. Mathar, Oct 18 2009

STATUS

approved

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Last modified August 9 01:35 EDT 2020. Contains 336310 sequences. (Running on oeis4.)