%I #11 Sep 08 2022 08:45:16

%S 2,4,16,19,20,23,29,40,43,50,59,62,71,83,89,107,115,116,122,134,145,

%T 155,157,160,167,184,197,218,250,251,262,268,278,284,289,292,298,311,

%U 314,335,344,346,347,349,353,355,361,362,379,389,398,400,401,425,431,437,439,452,457,470,475,485,491

%N Numbers k such that k999999 is prime.

%e If k=2, then k999999 = 2999999 (prime).

%e If k=43, then k999999 = 43999999 (prime).

%e If k=89, then k999999 = 89999999 (prime).

%o (Magma) [ n: n in [1..700] | IsPrime(Seqint([9,9,9,9,9,9] cat Intseq(n))) ]; // _Vincenzo Librandi_, Feb 04 2011

%K base,nonn

%O 1,1

%A _Parthasarathy Nambi_, Feb 24 2005