The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A062060 Numbers with 10 odd integers in their Collatz (or 3x+1) trajectory. 13
 43, 86, 87, 89, 172, 173, 174, 177, 178, 179, 344, 346, 348, 349, 354, 355, 356, 357, 358, 385, 423, 688, 692, 693, 696, 698, 705, 708, 709, 710, 712, 714, 716, 717, 729, 761, 769, 770, 771, 777, 846, 847, 1376, 1384, 1386, 1392, 1393, 1396, 1397, 1410, 1411, 1415 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS The Collatz (or 3x+1) function is f(x) = x/2 if x is even, 3x+1 if x is odd. The Collatz trajectory of n is obtained by applying f repeatedly to n until 1 is reached. A078719(a(n)) = 10; A006667(a(n)) = 9. REFERENCES J. Shallit and D. Wilson, The "3x+1" Problem and Finite Automata, Bulletin of the EATCS #46 (1992) pp. 182-185. LINKS Reinhard Zumkeller, Table of n, a(n) for n = 1..10000 J. Shallit and D. Wilson, The "3x+1" Problem and Finite Automata, Bulletin of the EATCS #46 (1992) pp. 182-185. Eric Weisstein's World of Mathematics, Collatz Problem Wikipedia, Collatz conjecture EXAMPLE The Collatz trajectory of 43 is (43, 130, 65, 196, 98, 49, 148, 74, 37, 112, 56, 28, 14, 7, 22, 11, 34, 17, 52, 26, 13, 40, 20, 10, 5, 16, 8, 4, 2, 1), which contains 10 odd integers. MATHEMATICA Collatz[n_] := NestWhileList[If[EvenQ[#], #/2, 3 # + 1] &, n, # > 1 &]; countOdd[lst_] := Length[Select[lst, OddQ]]; Select[Range[1000], countOdd[Collatz[#]] == 10 &] (* T. D. Noe, Dec 03 2012 *) PROG (Haskell) import Data.List (elemIndices) a062060 n = a062060_list !! (n-1) a062060_list = map (+ 1) \$ elemIndices 10 a078719_list -- Reinhard Zumkeller, Oct 08 2011 (Python) def a(n):     l=[n, ]     while True:         if n%2==0: n/=2         else: n = 3*n + 1         if not n in l:             l+=[n, ]             if n<2: break         else: break     return len(list(filter(lambda i: i%2==1, l))) print [n for n in range(40, 1501) if a(n)==10] # Indranil Ghosh, Apr 14 2017 CROSSREFS Cf. A062052-A062059. Sequence in context: A247436 A063351 A065874 * A037986 A198593 A039526 Adjacent sequences:  A062057 A062058 A062059 * A062061 A062062 A062063 KEYWORD nonn,look AUTHOR STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified August 12 12:09 EDT 2020. Contains 336439 sequences. (Running on oeis4.)