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 A268448 Numbers n such that (35*10^n - 11)/3 is prime. 504

%I

%S 1,2,4,5,6,7,14,21,27,34,53,72,96,145,168,191,192,309,393,502,667,

%T 1055,1534,1710,4171,4838,4950,9932,10860,11906,14148,17184,27054,

%U 31435

%N Numbers n such that (35*10^n - 11)/3 is prime.

%C Numbers n such that digits 11 followed by n-1 occurrences of digit 6 followed by digit 3 is prime. E.g., 116666...666663.

%C a(35) > 10^5. - _Robert Price_, Oct 16 2015

%H Makoto Kamada, <a href="https://stdkmd.net/nrr/prime/primedifficulty.txt">Search for 116w3.</a>

%e 7 is in this sequence because (35*10^7 - 11)/3 = 116666663 is prime.

%t Select[Range[0, 100000], PrimeQ[(35*10^# - 11)/3] &]

%o (MAGMA) [n: n in [0..400] |IsPrime((35*10^n-11) div 3)]; // _Vincenzo Librandi_, Feb 05 2016

%o (PARI) lista(nn) = {for(n=1, nn, if(ispseudoprime((35*10^n-11)/3), print1(n, ", ")));} \\ _Altug Alkan_, Feb 05 2016

%Y Cf. A056654.

%K more,nonn

%O 1,2

%A _Robert Price_, Feb 04 2016

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Last modified February 23 12:35 EST 2019. Contains 320431 sequences. (Running on oeis4.)