OFFSET
1,1
LINKS
Robert Israel, Table of n, a(n) for n = 1..10000
EXAMPLE
Note that 2 and 929 are not emirps because they are palindromes.
MAPLE
Dmax:= 6: # to get all terms with up to Dmax digits
Res:= NULL:
npd:= [0, 1, 4, 6, 8, 9]:
for dd from 3 to Dmax do
R:= [seq(seq([seq(npd[j+1], j=convert(6*x+j, base, 6))],
x=[$6^(dd-3) .. 2*6^(dd-3)-1, $5*6^(dd-3)..6^(dd-2)-1]), j=[1, 5])];
for p from 2 to dd-1 do
for r in R do
x:= [op(r[1..p-1]), 2, op(r[p..-1])];
v1:= add(x[i]*10^(i-1), i=1..dd);
v2:= add(x[-i]*10^(i-1), i=1..dd);
if v1 < v2 and isprime(v1) and isprime(v2) then Res:= Res, v1, v2; if min(v1, v2) < 10^3 then print(dd, p, r, x, v1, v2) fi fi
od od od:
sort([Res]); # Robert Israel, Jun 02 2016
MATHEMATICA
emrp[n_]:=Module[{idn=IntegerDigits[n], rev}, rev=Reverse[idn]; PrimeQ[FromDigits[rev]]&&rev!=idn]
only2[n_]:=DigitCount[n, 10, {3, 5, 7}]=={0, 0, 0}&&DigitCount[n, 10, 2]==1
Select[Select[Prime[Range[10000]], emrp], only2] (* Harvey P. Dale, Jan 22 2011 *)
CROSSREFS
KEYWORD
base,less,nonn
AUTHOR
Lekraj Beedassy, Jun 25 2010
EXTENSIONS
Terms confirmed by Ray Chandler, Jul 13 2010
Definition improved by Harvey P. Dale, Jul 17 2010
STATUS
approved