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 A293534 Numbers k such that 22*10^k + 3 is prime. 0
 1, 2, 3, 6, 15, 18, 26, 51, 54, 68, 85, 242, 597, 2335, 3463, 4160, 5565, 8322, 11389, 43982, 70729, 127645, 151998 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS For k > 0, numbers k such that the digits 22 followed by k-1 occurrences of the digit 0 followed by the digit 3 is prime (see Example section). a(24) > 2*10^5. LINKS Table of n, a(n) for n=1..23. Makoto Kamada, Factorization of near-repdigit-related numbers. Makoto Kamada, Search for 220w3. EXAMPLE 2 is in this sequence because 22*10^2 + 3 = 2203 is prime. Initial terms and associated primes: a(1) = 1, 223; a(2) = 2, 2203; a(3) = 3, 22003; a(4) = 6, 22000003; a(5) = 15, 22000000000000003; etc. MATHEMATICA Select[Range[0, 100000], PrimeQ[22*10^# + 3] &] PROG (PARI) isok(k) = isprime(22*10^k + 3); \\ Altug Alkan, Oct 11 2017 CROSSREFS Cf. A056654, A268448, A269303, A270339, A270613, A270831, A270890, A270929, A271269. Sequence in context: A335260 A090983 A198684 * A066653 A081945 A329745 Adjacent sequences: A293531 A293532 A293533 * A293535 A293536 A293537 KEYWORD nonn,more,hard AUTHOR Robert Price, Oct 11 2017 EXTENSIONS a(22)-a(23) from Robert Price, Jan 04 2020 STATUS approved

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Last modified July 19 17:03 EDT 2024. Contains 374410 sequences. (Running on oeis4.)