|
Search: id:A033959
|
|
|
| A033959 |
|
Record number of steps to reach 1 in `3x+1' problem, corresponding to starting values in A033958. |
|
+0
3
|
|
| 0, 2, 5, 6, 7, 41, 42, 43, 44, 45, 46, 47, 52, 62, 65, 66, 76, 79, 87, 96, 98, 101, 102, 103, 113, 114, 119, 125, 129, 130, 138, 141, 142, 164, 166, 174, 189, 195, 196, 197, 207, 208, 209, 217, 222, 228, 248, 256, 257, 258, 263, 278, 357, 358, 359, 362, 370
(list; graph; listen)
|
|
|
OFFSET
|
0,2
|
|
|
COMMENT
|
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.
B. Hayes, Computer Recreations: On the ups and downs of hailstone numbers, Scientific American, 250 (No. 1, 1984), pp. 10-16.
G. T. Leavens and M. Vermeulen, 3x+1 search problems, Computers and Mathematics with Applications, 24 (1992), 79-99.
|
|
LINKS
|
Index entries for sequences from "Goedel, Escher, Bach"
Index entries for sequences related to 3x+1 (or Collatz) problem
|
|
MAPLE
|
A033959 := proc(n) local a, L; L := 0; a := n; while a <> 1 do if a mod 2 = 0 then a := a/2; else a := 3*a+1; L := L+1; fi; od: RETURN(L); end;
|
|
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 ] ] ] ]
|
|
CROSSREFS
|
Cf. A006884, A006885, A006877, A006878, A033492, A033958.
Sequence in context: A111300 A117548 A014489 this_sequence A159752 A126971 A090946
Adjacent sequences: A033956 A033957 A033958 this_sequence A033960 A033961 A033962
|
|
KEYWORD
|
nonn,nice
|
|
AUTHOR
|
N. J. A. Sloane (njas(AT)research.att.com).
|
|
EXTENSIONS
|
More terms from Winston C. Yang (winston(AT)cs.wisc.edu), Aug 27 2000 and from Larry Reeves (larryr(AT)acm.org), Sep 27 2000
|
|
|
Search completed in 0.002 seconds
|
