A137836 Emirps using only and all of the prime digits 2,3,5,7.

3257, 3527, 7253, 7523, 32257, 32537, 35227, 35257, 35327, 72253, 72353, 73523, 75223, 75253, 322573, 327553, 332573, 355723, 375223, 375233, 725357, 753527, 3223357, 3223537, 3225737, 3235577, 3235777, 3237527, 3252377, 3253753

Offset: 1

Author

Lekraj Beedassy, Feb 12 2008

Keywords

• nonn
• base

Links

• Marius A. Burtea, Table of n, a(n) for n = 1..1601 (up to 10^9)

Crossrefs

Subsequence of A128388.

Programs

Maple

read transforms : isA006567 := proc(n) local nrev ; if isprime(n) then nrev := digrev(n) ; nrev <> n and isprime(nrev)) ; else false ; fi ; end: isA137836 := proc(n) local dgs ; if isA006567(n) then dgs := convert(convert(n,base,10),set) ; if dgs minus {2,3,5,7} <> {} then false ; elif nops(dgs) <> 4 then false ; else true ; fi ; else false ; fi ; end: for n from 1 to 1000000 do p := ithprime(n) ; if isA137836(p) then print(p) ; fi ; od: # R. J. Mathar, Feb 28 2008

Mathematica

Take[With[{nn=2},Union[FromDigits/@Select[Select[Flatten[Permutations/@ Flatten[ Table[Join[{2,3,5,7},Table[2,{i}],Table[3,{j}],Table[5,{k}], Table[7,{l}]],{i,0,nn},{j,0,nn},{k,0,nn},{l,0,nn}],3],1], PrimeQ[ FromDigits[#]]&], PrimeQ[FromDigits[Reverse[#]]]&]]],100] (* Harvey P. Dale, Nov 07 2012 *)

Extensions

Corrected and extended by R. J. Mathar, Feb 28 2008