OFFSET
1,1
LINKS
Harvey P. Dale, Table of n, a(n) for n = 1..1000
EXAMPLE
11 is prime and it has two nonprime digits, twice 1;
2269 is prime and it has two nonprime digits, 6 and 9.
MAPLE
stev_sez:=proc(n) local i, tren, st, ans, anstren; ans:=[ ]: anstren:=[ ]: tren:=n: for i while (tren>0) do st:=round( 10*frac(tren/10) ): ans:=[ op(ans), st ]: tren:=trunc(tren/10): end do; for i from nops(ans) to 1 by -1 do anstren:=[ op(anstren), op(i, ans) ]; od; RETURN(anstren); end: ts_stnepf:=proc(n) local i, stpf, ans; ans:=stev_sez(n): stpf:=0: for i from 1 to nops(ans) do if (isprime(op(i, ans))='false') then stpf:=stpf+1; # number of nonprime digits fi od; RETURN(stpf) end: ts_pr_neprnd:=proc(n) local i, stpf, ans, ans1, tren; ans:=[ ]: stpf:=0: tren:=1: for i from 1 to n do if ( isprime(i)='true' and ts_stnepf(i) = 2) then ans:=[ op(ans), i ]: tren:=tren+1; fi od; RETURN(ans) end: ts_pr_neprnd(4000);
MATHEMATICA
npd2Q[n_]:=Count[IntegerDigits[n], _?(!PrimeQ[#]&)]==2; Select[Prime[ Range[ 200]], npd2Q] (* Harvey P. Dale, May 12 2015 *)
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Jani Melik, Apr 11 2004
STATUS
approved