|
| |
|
|
A098217
|
|
Cototients of terms from A098216. By definitions these cototient vakues are decimal repdigits.
|
|
1
| |
|
|
0, 2, 4, 4, 3, 6, 8, 8, 7, 8, 9, 5, 9, 22, 11, 7, 44, 44, 66, 33, 88, 11, 33, 55, 88, 55, 99, 111, 77, 33, 99, 99, 111, 77, 77, 111, 55, 333, 55, 77, 444, 99, 333, 333, 77, 111, 77, 99, 77, 77, 777, 888, 888, 111, 99, 999, 777, 111, 99, 99, 555, 111, 999, 999, 999, 111, 1111
(list; graph; refs; listen; history; internal format)
|
|
|
|
OFFSET
| 1,2
|
|
|
COMMENTS
| It is believed that for every repdigit r>1, inverse[cototient[r]] has solution, usually more than one.
|
|
|
MATHEMATICA
| ta={{0}}; Do[s=Length[Union[IntegerDigits[n-EulerPhi[n]]]]; If[Equal[s, 1]&&!PrimeQ[n], Print[{n, n-EulerPhi[n]}]; ta=Append[ta, n]], {n, 1, 100000}]; ta=Delete[ta, 1]; ta-EulerPhi[ta]
|
|
|
CROSSREFS
| Cf. A096503, A010785.
Sequence in context: A079533 A072872 A135359 * A151846 A131118 A140765
Adjacent sequences: A098214 A098215 A098216 * A098218 A098219 A098220
|
|
|
KEYWORD
| nonn,base
|
|
|
AUTHOR
| Labos E. (labos(AT)ana.sote.hu), Oct 22 2004
|
| |
|
|
