

A070974


Number of steps to reach 1 in `3x+1' (or Collatz) problem starting with n!.


0



0, 1, 8, 10, 20, 20, 41, 44, 86, 66, 147, 210, 175, 264, 255, 259, 426, 425, 362, 387, 500, 489, 447, 449, 389, 559, 419, 517, 633, 444, 529, 534, 795, 950, 826, 813, 1069, 689, 728, 785, 909, 819, 1013, 1171, 1218, 996, 1327, 1330, 891, 1295, 1342, 1402
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OFFSET

1,3


LINKS

Table of n, a(n) for n=1..52.


MATHEMATICA

ns[n_]:=Length[NestWhileList[If[EvenQ[#], #/2, 3#+1]&, n!, #!=1&]]1; Array[ ns, 60] (* Harvey P. Dale, Jan 17 2013 *)


PROG

(PARI) for(n=2, 100, s=n!; t=0; while(s!=1, t++; if(s%2==0, s=s/2, s=3*s+1); if(s==1, print1(t, ", "); ); ))


CROSSREFS

Sequence in context: A302637 A230862 A281067 * A300022 A073619 A338820
Adjacent sequences: A070971 A070972 A070973 * A070975 A070976 A070977


KEYWORD

easy,nonn


AUTHOR

Benoit Cloitre, May 17 2002


STATUS

approved



