A092629 Numbers that have a nonprime number of prime digits.
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, 31, 34, 36, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 54, 56, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 74, 76, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88
Offset: 1
Examples
24 has one prime digit 2 and their number 1 is nonprime; 235719 has four prime digits 2,3,5,7 and their number 4 is nonprime. 313 is not in the sequence as it has a prime number (2) of prime digits (3, 3). - _David A. Corneth_, Aug 09 2023
Crossrefs
Cf. A019546.
Programs
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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_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);
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Mathematica
Select[Range[100],!PrimeQ[Count[IntegerDigits[#],?PrimeQ]]&] (* _Harvey P. Dale, Jan 15 2013 *)
Extensions
Edited by Charles R Greathouse IV, Aug 03 2010