A217039 Primes having only {4, 5, 7} as digits.

5, 7, 47, 457, 547, 557, 577, 757, 4447, 4457, 4547, 5477, 5557, 7457, 7477, 7547, 7577, 7757, 44777, 45557, 45757, 47777, 54547, 54577, 55457, 55547, 57457, 57557, 74747, 75557, 75577, 77447, 77477, 77557, 77747, 444547, 444557, 445447, 445477, 445747, 447757

Offset: 1

Author

Jonathan Vos Post, Sep 24 2012

Keywords

• nonn
• base
• easy

Comments

These are the primes in A214584. Primes whose numerals are all written (san serif) with at least one right or acute angle.

Links

• Jason Bard, Table of n, a(n) for n = 1..10000
• Index to entries for primes with digits in a given set

Crossrefs

Cf. A079651, A079652, A214584.

Cf. A036953, A260044, A260267 - A260271, A199325 - A199329, A061247, A199340 - A199349.

Programs

Magma

[p: p in PrimesUpTo(450000) | Intseq(p) subset [4,5,7]]; // Bruno Berselli, Sep 25 2012

Mathematica

Select[Flatten[Table[FromDigits/@Tuples[{4,5,7},n],{n,6}]],PrimeQ] (* Bruno Berselli, Sep 25 2012 *)

PARI

A217039(n=50,show=0,L=[4,5,7])={for(d=1,1e9, my(t, u=vector(d,i,10^(d-i))~); forvec(v=vector(d,i,[if(i==d&&d>1,3/*must end in 7*/,1), #L]), ispseudoprime(t=vecextract(L, v)*u)||next; show&&print1(t", "); n--||return(t)))} \\ Syntax updated for newer PARI versions by M. F. Hasler, Jul 25 2015

Formula

A000040 INTERSECTION A214584.