%I
%S 1,3,21,33,1083,2541,51282,51282,1296060612,43449172767,189324538095
%N Smallest k such that concatenation of r*k and 1 is a prime for all r = 1 to n, or smallest k such that 10*r*k +1 is a prime for all r = 1 to n.
%C The primes arising in triangular form are
%C 11
%C 31 61
%C 211 421 631
%C 331 661 991 1321
%C ...
%C Next term is > 1.38*10^12.  _David Wasserman_, Sep 13 2005
%K base,hard,nonn
%O 1,2
%A _Amarnath Murthy_, Nov 03 2003
%E More terms from _Ray G. Opao_, Jan 13 2005
%E 3 more terms from _David Wasserman_, Sep 13 2005
