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!)
 A056959 In repeated iterations of function m -> m/2 if m even, m -> 3m+1 if m odd, a(n) is maximum value achieved if starting from n. 3
 4, 4, 16, 4, 16, 16, 52, 8, 52, 16, 52, 16, 40, 52, 160, 16, 52, 52, 88, 20, 64, 52, 160, 24, 88, 40, 9232, 52, 88, 160, 9232, 32, 100, 52, 160, 52, 112, 88, 304, 40, 9232, 64, 196, 52, 136, 160, 9232, 48, 148, 88, 232, 52, 160, 9232, 9232, 56, 196, 88, 304, 160, 184 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS If a(n) exists (which is the essence of the "3x+1" problem) then a(n) must be a multiple of 4, since if a(n) was odd then the next iteration 3*a(n)+1 would be greater than a(n), while if a(n) was twice an odd number then the next-but-one iteration (3/2)*a(n)+1 would be greater. The variant A025586 considers the trajectory ending in 1, by definition. Therefore the two sequences differ for a(1) and a(2). - M. F. Hasler, Oct 20 2019 LINKS EXAMPLE a(6)=16 since iteration starts: 6, 3, 10, 5, 16, 8, 4, 2, 1, 4, 2, 1, ... and 16 is highest value PROG (PARI) a(n)=my(r=max(4, n)); while(n>2, if(n%2, n=3*n+1; if(n>r, r=n), n/=2)); r \\ Charles R Greathouse IV, Jul 19 2011 CROSSREFS Cf. A006370, A056957, A056958. Essentially the same as A025586. Sequence in context: A177241 A076821 A165825 * A255300 A255298 A255302 Adjacent sequences:  A056956 A056957 A056958 * A056960 A056961 A056962 KEYWORD nonn AUTHOR Henry Bottomley, Jul 18 2000 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 January 22 12:52 EST 2021. Contains 340362 sequences. (Running on oeis4.)