A179033 Emirps with a single 2 as the only prime digit.
1021, 1201, 1249, 1429, 9029, 9209, 9241, 9421, 10429, 11621, 12109, 12119, 12149, 12491, 12611, 12619, 12641, 12689, 12809, 12841, 12919, 14029, 14621, 14629, 14821, 14929, 16249, 16829, 18269, 19219, 19249, 19421, 90121, 90821, 91121
Offset: 1
Examples
Note that 2 and 929 are not emirps because they are palindromes.
Links
- Robert Israel, Table of n, a(n) for n = 1..10000
Programs
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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 *)
Extensions
Terms confirmed by Ray Chandler, Jul 13 2010
Definition improved by Harvey P. Dale, Jul 17 2010