A092628 Primes with exactly three nonprime digits.

101, 109, 149, 181, 191, 199, 401, 409, 419, 449, 461, 491, 499, 601, 619, 641, 661, 691, 809, 811, 881, 911, 919, 941, 991, 1013, 1021, 1031, 1039, 1051, 1063, 1087, 1093, 1097, 1103, 1117, 1129, 1151, 1163, 1171, 1187, 1193, 1201, 1249, 1289, 1291

Offset

1,1

Links

Harvey P. Dale, Table of n, a(n) for n = 1..1000

Example

101 is prime and it has three nonprime digits, 0 and twice 1;
4261 is prime and it has three nonprime digits, 1, 4 and 6.

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_neprnt:=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) = 3) then ans:=[ op(ans), i ]: tren:=tren+1; fi od; RETURN(ans) end: ts_pr_neprnt(5000);

Mathematica

dgQ[n_]:=Count[IntegerDigits[n], _?(!PrimeQ[#]&)]==3; Select[Prime[ Range[300]], dgQ] (* Harvey P. Dale, Oct 11 2011 *)

Crossrefs

Cf. A019546, A034844.

Sequence in context: A344802 A126118 A118773 * A107219 A366106 A140799

Adjacent sequences: A092625 A092626 A092627 * A092629 A092630 A092631

Keyword

nonn,base

Author

Jani Melik, Apr 11 2004

Status

approved