|
|
A117283
|
|
Numbers k for which the cototient k-phi(k) is a cube.
|
|
7
|
|
|
1, 2, 3, 5, 7, 11, 12, 13, 14, 16, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 63, 67, 71, 73, 79, 81, 83, 89, 96, 97, 101, 103, 107, 109, 112, 113, 115, 124, 127, 128, 131, 137, 139, 149, 151, 157, 163, 167, 173, 179, 181, 187, 191, 193, 197, 199, 211, 223, 227
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
1,2
|
|
LINKS
|
|
|
EXAMPLE
|
63 is in the sequence because 63-phi(63) = 27, which is a cube.
|
|
MATHEMATICA
|
|
|
PROG
|
(PARI) isok(k) = ispower(k-eulerphi(k), 3); \\ Michel Marcus, Mar 23 2021
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
Luc Stevens (lms022(AT)yahoo.com), Apr 23 2006
|
|
STATUS
|
approved
|
|
|
|