login
Numbers k such that k11111 is prime.
0

%I #14 Sep 08 2022 08:45:16

%S 3,5,6,9,20,24,26,39,42,48,60,65,68,83,84,93,95,108,119,126,132,146,

%T 167,179,182,189,203,206,213,224,227,230,233,234,249,258,269,270,272,

%U 291,296,305,315,324,329,336,341,345,347,348,363,368,377,384,387,392,402,422,423,438,440,450,455,458

%N Numbers k such that k11111 is prime.

%e If k=3, then k11111 = 311111 (prime).

%e If k=60, then k11111 = 6011111 (prime).

%e If k=126, then k11111 = 12611111 (prime).

%t Select[Range[500],PrimeQ[100000#+11111]&] (* _Harvey P. Dale_, Jan 15 2013 *)

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

%Y Cf. A101471, A102248, A102249.

%K base,nonn

%O 1,1

%A _Parthasarathy Nambi_, Feb 22 2005