A062087 Squarefree numbers with all prime digits.

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

Offset

1,1

Comments

Heuristically, there are about 4^n * 275/(48*Pi^2) n-digit terms of this sequence. - Charles R Greathouse IV, Oct 18 2011

Links

Amiram Eldar, Table of n, a(n) for n = 1..10000

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

Intersection of A046034 and A005117.

Sequence in context: A085557 A125665 A046034 * A162457 A084983 A062239

Adjacent sequences: A062084 A062085 A062086 * A062088 A062089 A062090

Keyword

nonn,base

Author

Amarnath Murthy, 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

Status

approved