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 A110920 Integers n such that 2*10^n + 81 is a prime number. 0
 0, 1, 2, 3, 6, 7, 8, 15, 36, 38, 51, 168, 1000, 2955, 8151, 16456, 17902, 18784, 24948, 28731, 87144 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,3 COMMENTS See Kamada link - primecount.txt for terms, primesize.txt for discovery details including probable or proved primes - search on "20081". a(22) > 10^5. - Robert Price, Jan 19 2017 LINKS Table of n, a(n) for n=1..21. Makoto Kamada, List of near-repdigit-related prime numbers. Index entries for primes involving repunits. EXAMPLE n = 3 is a term because 2*10^3 + 81 = 2*1000 + 81 = 2000 + 81 = 2081 and 2081 is prime. CROSSREFS Cf. A049054, A088274, A088275, A095688, A107083, A108049, A108050, A108052, A108054. Sequence in context: A030164 A066646 A215488 * A296414 A267590 A145266 Adjacent sequences: A110917 A110918 A110919 * A110921 A110922 A110923 KEYWORD more,nonn AUTHOR Julien Peter Benney (jpbenney(AT)ftml.net), Oct 04 2005 EXTENSIONS a(15)-a(18) from Kamada link by Ray Chandler, Dec 23 2010 a(1)-a(2) prepended by Robert Price, Jan 19 2017 a(19)-a(21) from Robert Price, Jan 19 2017 STATUS approved

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Last modified May 26 23:01 EDT 2024. Contains 372847 sequences. (Running on oeis4.)