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 A284741 Numbers k such that (29*10^k + 259)/9 is prime. 0
 1, 3, 4, 6, 9, 10, 24, 27, 66, 76, 136, 346, 399, 978, 1228, 2227, 4005, 5916, 6394, 7438, 18934, 20020, 31866, 85438 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS For k>1, numbers such that the digit 3 followed by k-2 occurrences of the digit 2 followed by the digits 51 is prime (see Example section). a(25) > 10^5. LINKS Makoto Kamada, Factorization of near-repdigit-related numbers. Makoto Kamada, Search for 32w51. EXAMPLE 3 is in this sequence because (29*10^3 + 259)/9 = 3251 is prime. Initial terms and primes associated: a(1) = 1, 61; a(2) = 3, 3251; a(3) = 4, 32251; a(4) = 6, 3222251; a(5) = 9, 3222222251; etc. MATHEMATICA Select[Range[0, 100000], PrimeQ[(29*10^# + 259)/9] &] CROSSREFS Cf. A056654, A268448, A269303, A270339, A270613, A270831, A270890, A270929, A271269. Sequence in context: A268110 A124093 A025061 * A037969 A153236 A158705 Adjacent sequences:  A284738 A284739 A284740 * A284742 A284743 A284744 KEYWORD nonn,more,hard AUTHOR Robert Price, Apr 01 2017 STATUS approved

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Last modified May 26 09:12 EDT 2017. Contains 287093 sequences.