cp's OEIS Frontend

A092629 Numbers that have a nonprime number of prime digits.

%I A092629 #15 Sep 11 2023 23:18:03
%S A092629 1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,24,26,28,29,30,
%T A092629 31,34,36,38,39,40,41,42,43,44,45,46,47,48,49,50,51,54,56,58,59,60,61,
%U A092629 62,63,64,65,66,67,68,69,70,71,74,76,78,79,80,81,82,83,84,85,86,87,88
%N A092629 Numbers that have a nonprime number of prime digits.
%e A092629 24 has one prime digit 2 and their number 1 is nonprime;
%e A092629 235719 has four prime digits 2,3,5,7 and their number 4 is nonprime.
%e A092629 313 is not in the sequence as it has a prime number (2) of prime digits (3, 3). - _David A. Corneth_, Aug 09 2023
%p A092629 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_stpf:=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))='true') then stpf:=stpf+1; # number of prime digits fi od; RETURN(stpf) end: ts_nepr:=proc(n) local i, stpf, ans, ans1; ans:=[ ]: stpf:=0: for i from 1 to n do if (isprime( ts_stpf(i) )='false') then ans:=[ op(ans), i ]: fi od; RETURN(ans) end: ts_nepr(600);
%t A092629 Select[Range[100],!PrimeQ[Count[IntegerDigits[#],_?PrimeQ]]&] (* _Harvey P. Dale_, Jan 15 2013 *)
%Y A092629 Cf. A019546.
%K A092629 nonn,easy,base
%O A092629 1,2
%A A092629 _Jani Melik_, Apr 11 2004
%E A092629 Edited by _Charles R Greathouse IV_, Aug 03 2010