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 A294570 Numbers k such that (58*10^k + 329)/9 is prime. 0
 0, 1, 3, 6, 19, 22, 27, 48, 70, 130, 364, 594, 603, 799, 2442, 3168, 5059, 5563, 6523, 12282, 13498, 34099, 86242, 122170, 161691 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,3 COMMENTS For k>1, numbers such that the digit 6 followed by k-2 occurrences of the digit 4 followed by the digits 81 is prime (see Example section). a(26) > 2*10^5. LINKS Makoto Kamada, Factorization of near-repdigit-related numbers. Makoto Kamada, Search for 64w81. EXAMPLE 3 is in this sequence because (58*10^3 + 329)/9 = 6481 is prime. Initial terms and primes associated: a(1) = 0, 43; a(2) = 1, 101; a(3) = 3, 6481; a(4) = 6, 6444481; a(5) = 19, 64444444444444444481; etc. MATHEMATICA Select[Range[0, 100000], PrimeQ[(58*10^# + 329)/9] &] CROSSREFS Cf. A056654, A268448, A269303, A270339, A270613, A270831, A270890, A270929, A271269. Sequence in context: A057268 A085401 A085061 * A306968 A090956 A108972 Adjacent sequences:  A294567 A294568 A294569 * A294571 A294572 A294573 KEYWORD nonn,more,hard AUTHOR Robert Price, Nov 02 2017 EXTENSIONS a(24)-a(25) from Robert Price, May 01 2019 STATUS approved

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Last modified November 30 18:31 EST 2021. Contains 349424 sequences. (Running on oeis4.)