|
Search: id:A055506
|
|
|
| A055506 |
|
Number of x with EulerPhi[x] = n!. |
|
+0
2
|
|
| 2, 3, 4, 10, 17, 49, 93, 359, 1138, 3802, 12124, 52844, 182752, 696647, 2852886, 16423633, 75301815, 367900714, 1531612895, 8389371542
(list; graph; listen)
|
|
|
OFFSET
|
1,1
|
|
|
COMMENT
|
Note that if Phi[x] = n!, then x must be a product of primes p such that p - 1 divides n!. - David Wasserman (wasserma(AT)spawar.navy.mil), Apr 30 2002
|
|
FORMULA
|
a(n) = A014197(n!) = Cardinality[{x; A000010(x) = A000142(n)}]
|
|
EXAMPLE
|
n = 5, Phi[x] = 5! = 120 holds for the following 17 numbers: {143,155,175,183,225,231,244,248,286,308,310,350,366,372,396,450,462}
|
|
CROSSREFS
|
Cf. A000142, A000010, A014197, A000203, A054873, A067847, A055486.
Adjacent sequences: A055503 A055504 A055505 this_sequence A055507 A055508 A055509
Sequence in context: A115899 A085934 A056701 this_sequence A098088 A080500 A007661
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
Labos E. (labos(AT)ana.sote.hu), Jun 29 2000
|
|
EXTENSIONS
|
More terms from Jud McCranie (j.mccranie(AT)comcast.net), Jan 02 2001
More terms from David Wasserman (wasserma(AT)spawar.navy.mil), Apr 30 2002 (with the assistance of Vladeta Jovovic and Sascha Kurz).
|
|
|
Search completed in 0.002 seconds
|
