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%I #16 Sep 08 2024 19:26:02
%S 7,61,601,600000001,6000000001,6000000000000001,600000000000000000001,
%T 600000000000000000000000001,600000000000000000000000000000000000001,
%U 6000000000000000000000000000000000000000000001,600000000000000000000000000000000000000000000000000000000000000001
%N Primes of the form 6*10^n+1.
%H Makoto Kamada, <a href="https://stdkmd.net/nrr/6/60001.htm#prime">Prime numbers of the form 600...001</a>.
%t Select[Table[6*10^n+1,{n,0,70}],PrimeQ] (* _Harvey P. Dale_, Feb 22 2015 *)
%o (Magma) [a: n in [0..250]|IsPrime(a) where a is 6*10^n+1];
%Y Cf. A056805.
%K nonn
%O 1,1
%A _Vincenzo Librandi_, Dec 10 2010