A092627 Primes with exactly two nonprime digits.

11, 19, 41, 61, 89, 103, 107, 113, 131, 139, 151, 163, 167, 179, 193, 197, 211, 241, 269, 281, 311, 349, 389, 421, 431, 439, 443, 463, 467, 479, 487, 509, 541, 569, 599, 607, 613, 617, 631, 643, 647, 659, 683, 701, 709, 719, 761, 769, 821, 829, 839, 859, 863

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

Cf. A019546.

Sequence in context: A322474 A084986 A034844 * A152313 A034303 A293166

Adjacent sequences: A092624 A092625 A092626 * A092628 A092629 A092630

Keyword

nonn,base

Author

Jani Melik, Apr 11 2004

Status

approved