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 A006460 Image of n after 3k iterates of '3x+1' map (k large). (Formerly M0304) 3
 1, 2, 2, 4, 4, 4, 2, 1, 2, 1, 4, 1, 1, 4, 4, 2, 1, 4, 4, 2, 2, 1, 1, 2, 4, 2, 1, 1, 1, 1, 2, 4, 4, 2, 2, 1, 1, 1, 2, 4, 2, 4, 4, 2, 2, 2, 4, 4, 1, 1, 1, 4, 4, 2, 2, 2, 4, 2, 4, 2, 2, 4, 4, 1, 1, 1, 1, 4, 4, 4, 1, 2, 2, 2, 4, 2, 2, 4, 4, 1, 2, 4, 4, 1, 1, 1, 1, 4, 1, 4, 4, 4, 4, 1, 1, 1, 2, 2, 2, 2, 2, 2, 1, 1, 4 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 REFERENCES R. K. Guy, Unsolved Problems in Number Theory, E16. N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence). LINKS Reinhard Zumkeller, Table of n, a(n) for n = 1..10000 M. Elia, Letter to N. J. A. Sloane, Jun. 1981 J. C. Lagarias, The 3x+1 problem and its generalizations, Amer. Math. Monthly, 92 (1985), 3-23. FORMULA For n > 2: a(n) = 4 if L = 0, otherwise L, where L = A139399(n) mod 3. - Reinhard Zumkeller, Nov 16 2013 MATHEMATICA f[n_] := If[EvenQ[n], n/2, 3 n + 1]; a[n_] := With[{ff = NestWhileList[f, n, {#1, #2, #3} != {4, 2, 1}&, 3]}, ff[[Switch[Mod[Length[ff], 3], 0, -3, 1, -1, 2, -2]]]]; Table[a[n], {n, 1, 100}] (* Jean-François Alcover, Aug 08 2022 *) PROG (Haskell) a006460 = f 0 where f k x | mod k 3 == 0 && x `elem` [1, 2, 4] = x | otherwise = f (k+1) (a006370 x) -- Reinhard Zumkeller, Nov 16 2013 CROSSREFS Cf. A006370, A076052 (partial sums), A139399. Sequence in context: A231731 A143358 A143729 * A064137 A329588 A104202 Adjacent sequences: A006457 A006458 A006459 * A006461 A006462 A006463 KEYWORD nonn,nice AUTHOR EXTENSIONS More terms from Larry Reeves (larryr(AT)acm.org), Apr 27 2001 STATUS approved

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Last modified November 26 21:15 EST 2022. Contains 358362 sequences. (Running on oeis4.)