|
| |
|
|
A062087
|
|
Squarefree numbers with all prime digits.
|
|
0
| |
|
|
2, 3, 5, 7, 22, 23, 33, 35, 37, 53, 55, 57, 73, 77, 222, 223, 227, 233, 235, 237, 253, 255, 257, 273, 277, 322, 323, 327, 335, 337, 353, 355, 357, 373, 377, 523, 527, 533, 535, 537, 553, 555, 557, 573, 577, 723, 727, 733, 737, 753, 755, 757, 773, 777, 2222, 2227
(list; graph; refs; listen; history; internal format)
|
|
|
|
OFFSET
| 1,1
|
|
|
COMMENTS
| Heuristically, there are about 4^n * 275/(48*Pi^2) n-digit members of this sequence. [Charles R Greathouse IV, Oct 18 2011]
|
|
|
EXAMPLE
| a(6)= 23, 2 and 3 are both primes.
|
|
|
MATHEMATICA
| Select[Range[3000], Abs[MoebiusMu[#]] == 1 && Union[PrimeQ[IntegerDigits[#]]] == {True} &] (* Alonso del Arte, Oct 18 2011 *)
|
|
|
CROSSREFS
| Sequence in context: A085557 A125665 A046034 * A162457 A084983 A062239
Adjacent sequences: A062084 A062085 A062086 * A062088 A062089 A062090
|
|
|
KEYWORD
| nonn,base
|
|
|
AUTHOR
| Amarnath Murthy (amarnath_murthy(AT)yahoo.com), Jun 16 2001
|
|
|
EXTENSIONS
| Corrected and extended by Larry Reeves (larryr(AT)acm.org), Jun 18 2001
Offset corrected by Arkadiusz Wesolowski, Oct 18 2011
|
| |
|
|
