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 A294678 Numbers k such that (26*10^k - 167)/3 is prime. 0
 1, 2, 27, 38, 51, 122, 200, 408, 422, 680, 732, 1128, 2448, 3237, 8964, 11208, 14970, 15769, 17411, 27813, 46521, 101537, 164643, 167861 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS For k>1, numbers such that the digit 8 followed by k-2 occurrences of the digit 6 followed by the digits 11 is prime (see Example section). a(25) > 2*10^5. LINKS Makoto Kamada, Factorization of near-repdigit-related numbers. Makoto Kamada, Search for 86w11. EXAMPLE 2 is in this sequence because (26*10^2 - 167)/3 = 811 is prime. Initial terms and primes associated: a(1) = 1, 31; a(2) = 2, 811; a(3) = 27, 8666666666666666666666666611; a(4) = 38, 866666666666666666666666666666666666611; a(5) = 51, 8666666666666666666666666666666666666666666666666611; etc. MAPLE P:=proc(k) if isprime((26*10^k - 167)/3) then k; fi; end: seq(P(i), i=1..46521); # Paolo P. Lava, Nov 07 2017 MATHEMATICA Select[Range[1, 100000], PrimeQ[(26*10^# - 167)/3] &] CROSSREFS Cf. A056654, A268448, A269303, A270339, A270613, A270831, A270890, A270929, A271269. Sequence in context: A226670 A277542 A273844 * A206585 A046735 A038625 Adjacent sequences:  A294675 A294676 A294677 * A294679 A294680 A294681 KEYWORD nonn,more,hard AUTHOR Robert Price, Nov 06 2017 EXTENSIONS a(22)-a(24) from Robert Price, Oct 08 2019 STATUS approved

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Last modified May 13 19:36 EDT 2021. Contains 343868 sequences. (Running on oeis4.)