A217039 - OEIS

A217039

Primes whose decimal representation has only digits in {4,5,7}.

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

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OFFSET

1,1

COMMENTS

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

LINKS

Table of n, a(n) for n=1..41.

FORMULA

A000040 INTERSECTION A214584.

MATHEMATICA

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

PROG

(Magma) [p: p in PrimesUpTo(450000) | Intseq(p) subset [4, 5, 7]]; // 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

CROSSREFS

Cf. A079651, A079652, A214584.

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

Sequence in context: A119787 A025530 A106114 * A299452 A110420 A210244

Adjacent sequences: A217036 A217037 A217038 * A217040 A217041 A217042

KEYWORD

nonn,base,easy

AUTHOR

Jonathan Vos Post, Sep 24 2012

STATUS

approved