

A133422


Number of steps to reach 1 under repeated applications of the "7x+1" map of A133421, or 1 if 1 is never reached.


1



0, 1, 1, 2, 1, 2, 4, 3, 2, 2, 12, 3, 9, 5, 2, 4, 6, 3, 21, 3, 5, 13, 6, 4, 2, 10, 3, 6, 10, 3, 47, 5, 13, 7, 5, 4, 13, 22, 10, 4, 8, 6, 46, 14, 3, 7, 16, 5, 50, 3, 7, 11, 51, 4, 13, 7, 22, 11, 10, 4, 9, 48, 6, 6, 10, 14, 19, 8, 7, 6, 17, 5, 10, 14, 3, 23, 7, 11, 17, 5, 4, 9, 14, 7, 7, 47, 11, 15
(list;
graph;
refs;
listen;
history;
text;
internal format)



OFFSET

1,4


COMMENTS

The 7x+1 map sends x to x/2 if x is even, x/3 if x is divisible by 3, x/5 if x is divisible by 5, otherwise 7x+1.


LINKS



MATHEMATICA

nxt[x_]:= Which[Mod[x, 2]==0, x/2, Mod[x, 3]==0, x/3, Mod[x, 5]==0, x/5, True, 7x+1]; Table[First[First[Position[NestList[nxt, i, 100], 1]]]1, {i, 50}]  _Harvey P. Dale_, Dec 27 2007


CROSSREFS



KEYWORD

nonn,easy


AUTHOR

_N. J. A. Sloane_, Nov 27 2007


EXTENSIONS

More terms from _Harvey P. Dale_, Dec 27 2007
More terms from _Sean A. Irvine_, Mar 29 2010


STATUS

approved



