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Primes whose decimal expansion consists of a string of 2's followed by a string of 3's.
6

%I #8 Jan 30 2013 10:38:46

%S 2,3,23,223,233,2333,23333,2222333,22222223,223333333,22222222223,

%T 22222223333,22222333333,22223333333,23333333333,222223333333,

%U 23333333333333333,2222222222222233333,2222222222333333333

%N Primes whose decimal expansion consists of a string of 2's followed by a string of 3's.

%t With[{nn=20},Sort[Select[Flatten[Table[FromDigits[Join[Table[2,{i}],Table[3,{j}]]],{i,0,nn},{j,0,nn}]],PrimeQ]]] (* _Harvey P. Dale_, Jan 30 2013 *)

%Y Cf. A020458, A141470, A141471, A141472.

%K nonn,base

%O 1,1

%A _Paul Curtz_, Jun 05 2008

%E Entry revised by _Ray Chandler_ and _N. J. A. Sloane_, Aug 14 2008