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A217039 Primes whose decimal representation has only digits in {4,5,7}. 4

%I #23 Sep 08 2022 08:46:04

%S 5,7,47,457,547,557,577,757,4447,4457,4547,5477,5557,7457,7477,7547,

%T 7577,7757,44777,45557,45757,47777,54547,54577,55457,55547,57457,

%U 57557,74747,75557,75577,77447,77477,77557,77747,444547,444557,445447,445477,445747,447757

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

%C 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.

%F A000040 INTERSECTION A214584.

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

%o (Magma) [p: p in PrimesUpTo(450000) | Intseq(p) subset [4,5,7]]; // _Bruno Berselli_, Sep 25 2012

%o (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

%Y Cf. A079651, A079652, A214584.

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

%K nonn,base,easy

%O 1,1

%A _Jonathan Vos Post_, Sep 24 2012

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Last modified March 29 06:57 EDT 2024. Contains 371265 sequences. (Running on oeis4.)