1,3

a(1)=a(2)=a(4)=0 as A006370(A006370(A006370(x)))=x for x=1,2,4 [corrected by Rémy Sigrist, Jun 28 2020];

a(n) = A006577(n) - 2 for n > 2 (if the conjecture holds).

For n>2: let L = a(n) mod 3, then A006460(n) = if L=0 then 4 else L. - Reinhard Zumkeller, Nov 17 2013

Reinhard Zumkeller, 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

(Haskell)

a139399 = f 0 where

f k x = if x `elem` [1, 2, 4] then k else f (k + 1) (a006370 x)

-- Reinhard Zumkeller, Nov 17 2013

Essentially the same sequence as A112695.

Cf. A006370, A006460.

Sequence in context: A197573 A019947 A193182 * A318525 A021669 A011511

Adjacent sequences: A139396 A139397 A139398 * A139400 A139401 A139402

nonn

Reinhard Zumkeller, Apr 18 2008

approved