A092627 - OEIS

%I #7 May 12 2015 18:53:15

%S 11,19,41,61,89,103,107,113,131,139,151,163,167,179,193,197,211,241,

%T 269,281,311,349,389,421,431,439,443,463,467,479,487,509,541,569,599,

%U 607,613,617,631,643,647,659,683,701,709,719,761,769,821,829,839,859,863

%N Primes with exactly two nonprime digits.

%H Harvey P. Dale, <a href="/A092627/b092627.txt">Table of n, a(n) for n = 1..1000</a>

%e 11 is prime and it has two nonprime digits, twice 1;

%e 2269 is prime and it has two nonprime digits, 6 and 9.

%p 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);

%t npd2Q[n_]:=Count[IntegerDigits[n],_?(!PrimeQ[#]&)]==2; Select[Prime[ Range[ 200]], npd2Q] (* _Harvey P. Dale_, May 12 2015 *)

%Y Cf. A019546.

%K nonn,base

%O 1,1

%A _Jani Melik_, Apr 11 2004