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

1,1

Links

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

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 *)

Crossrefs

Subsequence of A128388.

Sequence in context: A183656 A043606 A135134 * A251919 A338071 A234653

Adjacent sequences: A137833 A137834 A137835 * A137837 A137838 A137839

Keyword

nonn,base

Author

Lekraj Beedassy, Feb 12 2008

Extensions

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

Status

approved