|
|
A070974
|
|
Number of steps to reach 1 in `3x+1' (or Collatz) problem starting with n!.
|
|
3
|
|
|
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
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
1,3
|
|
LINKS
|
|
|
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
|
|
|
KEYWORD
|
easy,nonn
|
|
AUTHOR
|
|
|
STATUS
|
approved
|
|
|
|