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 A186521 Numbers n>0 such that (7*10^(n+2)+666)*10^n+7 is prime. 2
 1, 3, 6, 7, 49, 578, 793, 1322, 1392, 2392, 3066, 13479 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS Or, indices of primes in A046720. Rudolf Ondrejka calls these "beastly palindromic primes". Some of the larger entries may only correspond to probable primes. LINKS Chris Caldwell, The Prime Glossary, Beastly prime G. L. Honaker, Jr. and Chris Caldwell, Prime Curios! 76667 R. Ondrejka, The Top Ten: a Catalogue of Primal Configurations MATHEMATICA Select[Range[10^3], PrimeQ[(7*10^(# + 2) + 666)*10^# + 7] &] (* Arkadiusz Wesolowski, Sep 08 2011 *) CROSSREFS Cf. A046720, A186086. Sequence in context: A287502 A287538 A233209 * A067697 A137128 A256372 Adjacent sequences:  A186518 A186519 A186520 * A186522 A186523 A186524 KEYWORD more,nonn,base AUTHOR Arkadiusz Wesolowski, Feb 23 2011 EXTENSIONS Added a(12)=13479, Arkadiusz Wesolowski, Mar 16 2011. STATUS approved

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Last modified April 23 03:11 EDT 2021. Contains 343198 sequences. (Running on oeis4.)