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%I #8 Nov 21 2013 12:48:17
%S 10,14,16,18,40,44,46,48,49,60,64,66,68,69,80,81,84,86,88,90,91,94,96,
%T 98,99,102,105,112,115,117,120,121,124,126,128,129,130,134,136,138,
%U 142,143,145,147,150,154,156,158,159,162,165,170,171,174,176,178,182,183
%N Nonprime numbers with exactly two nonprime digits.
%e 10 is nonprime and has two nonprime digits, 0 and 1;
%e 963 is nonprime and 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_nepr_neprnd:=proc(n) local i, stpf, ans, ans1, tren; ans:=[ ]: stpf:=0: tren:=1: for i from 1 to n do if ( isprime(i)='false' and ts_stnepf(i) = 2) then ans:=[ op(ans), i ]: tren:=tren+1; fi od; RETURN(ans) end: ts_nepr_neprnd(1000);
%t npd2Q[n_]:=Count[IntegerDigits[n],_?(!PrimeQ[#]&)]==2; With[{nn=200}, Select[Complement[Range[nn],Prime[Range[PrimePi[nn]]]],npd2Q]] (* _Harvey P. Dale_, Feb 05 2012 *)
%K nonn,base
%O 1,1
%A _Jani Melik_, Apr 11 2004
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