|
|
A049117
|
|
Smallest number which when Euler phi function is repeatedly applied have not reached a power of 2 in n steps.
|
|
3
|
|
|
3, 7, 19, 47, 163, 487, 1307, 2879, 19683, 39367, 177147, 531441, 1594323, 4782969, 14348907, 43046721, 86093443, 258280327, 688747547, 3486784401, 10460353203
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
0,1
|
|
COMMENTS
|
Note that all terms so far are primes or powers of 3. Is it true that all terms have this form? - T. D. Noe, Oct 07 2013
|
|
LINKS
|
|
|
EXAMPLE
|
The corresponding iterated phi-sequences are:
{3, 2, 1},
{7, 6, 2, 1},
{19, 18, 6, 2, 1},
{47, 46, 22, 10, 4, 2, 1},
{163, 162, 54, 18, 6, 2, 1},
{487, 486, 162, 54, 18, 6, 2, 1}, ...
|
|
MATHEMATICA
|
a[n_] := Module[{i = 1}, While[IntegerQ[Log[2, Nest[EulerPhi, i, n]]], i++ ]; i]; (* Sam Handler (sam_5_5_5_0(AT)yahoo.com), Sep 04 2006 *)
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn,more
|
|
AUTHOR
|
|
|
EXTENSIONS
|
More terms from Sam Handler (sam_5_5_5_0(AT)yahoo.com), Sep 04 2006
|
|
STATUS
|
approved
|
|
|
|