The OEIS is supported by the many generous donors to the OEIS Foundation.

 Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 60th year, we have over 367,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”). Other ways to Give
 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A033958 In the '3x+1' problem, these values for the starting value set new records for number of steps to reach 1. 5
 1, 3, 7, 9, 25, 27, 73, 97, 129, 171, 231, 313, 327, 703, 871, 1161, 2463, 2919, 3711, 6171, 10971, 13255, 17647, 23529, 26623, 34239, 35655, 52527, 77031, 106239, 142587, 156159, 216367, 230631, 410011, 511935, 626331, 837799, 1117065, 1501353, 1723519, 2298025, 3064033 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS Only the 3x+1 steps, not the halving steps, are counted. REFERENCES D. R. Hofstadter, Goedel, Escher, Bach: an Eternal Golden Braid, Random House, 1980, p. 400. G. T. Leavens and M. Vermeulen, 3x+1 search problems, Computers and Mathematics with Applications, 24 (1992), 79-99. LINKS Charles R Greathouse IV, Table of n, a(n) for n = 1..71 Brian Hayes, Computer Recreations: On the ups and downs of hailstone numbers, Scientific American, 250 (No. 1, 1984), pp. 10-16. Index entries for sequences from "Goedel, Escher, Bach" Index entries for sequences related to 3x+1 (or Collatz) problem FORMULA Positions of records in A006667. - Sean A. Irvine, Jul 22 2020 MATHEMATICA f[ nn_ ] := Module[ {c, n}, c = 0; n = nn; While[ n != 1, If[ Mod[ n, 2 ] == 0, n /= 2, n = 3*n + 1; c++ ] ]; Return[ c ] ] maxx = -1; For[ n = 1, n <= 10^8, n++, Module[ {val}, val = f[ n ]; If[ val > maxx, maxx = val; Print[ n, " ", val ] ] ] ] (* Winston C. Yang (winston(AT)cs.wisc.edu), Aug 27 2000 *) PROG (Haskell) a033958 n = a033958_list !! (n-1) -- For definition of a033958_list: see A033959. -- Reinhard Zumkeller, Jan 08 2014 CROSSREFS Cf. A006884, A006885, A006877, A006878, A033492, A033959. Sequence in context: A099886 A118564 A098338 * A352016 A018827 A249664 Adjacent sequences: A033955 A033956 A033957 * A033959 A033960 A033961 KEYWORD nonn,nice AUTHOR N. J. A. Sloane EXTENSIONS More terms from Jud McCranie, Jan 26 2000 Corrected with Mathematica code by Winston C. Yang (winston(AT)cs.wisc.edu), Aug 27 2000 a(40)-a(43) from Charles R Greathouse IV, Oct 07 2013 STATUS approved

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

Last modified December 9 06:02 EST 2023. Contains 367685 sequences. (Running on oeis4.)