A164328 - OEIS

%I #8 Aug 13 2013 08:42:01

%S 7,11,271,1033,18289,133733,1045493,11939237,103333333,1342313221,

%T 10300335833,145933933339,1332523411733,11653733331833

%N a(n) is the smallest n-digit prime term of A158594 and zero if there is no such number.

%C It seems that for all n, a(n)>0.

%C A164327(n) gives us smallest n-digit term of A158594. So A164328(n)>=A164327(n).

%e a(5)=18289 so all the seven numbers 18289, 318289, 138289, 183289, 182389,

%e 182839 & 182893 are primes.

%t pp[n_, k_] := Catch[Block[{d = IntegerDigits@n}, Do[If[! PrimeQ[ FromDigits[ Insert[d, k, i]]], Throw[False]], {i, 1+Length@d}]; True]]; a[n_] := Catch[ Block[{p = NextPrime[10^(n-1)]}, While[p < 10^n, If[pp[p, 3], Throw@p, p = NextPrime@p]]; 0]]; a /@ Range[8] (* _Giovanni Resta_, Aug 13 2013 *)

%Y Cf. A158594, A164327, A164329, A228148-A228150.

%K base,hard,more,nonn

%O 1,1

%A _Farideh Firoozbakht_, Sep 22 2009

%E a(11)-a(13) from _Donovan Johnson_, Apr 14 2010

%E a(14) from _Giovanni Resta_, Aug 11 2013