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 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. 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 Charles R Greathouse IV, Table of n, a(n) for n = 1..71 MAPLE A033958 := 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 ] ] ] ] 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 * A018827 A249664 A057840 Adjacent sequences:  A033955 A033956 A033957 * A033959 A033960 A033961 KEYWORD nonn,nice AUTHOR 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

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