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 A219045 Numbers n such that 3^n - 26 is prime. 16
 7, 10, 13, 22, 27, 30, 57, 62, 117, 255, 535, 651, 873, 998, 1502, 18145, 22766, 25770, 43558, 45663, 48058, 62887, 87477, 103585, 115802 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS a(26) > 2*10^5. - Robert Price, Nov 20 2013 LINKS EXAMPLE For n=7, a(3)=3^7-26=2161 and 2161 is prime. Hence n=7 is included in the sequence. MATHEMATICA Do[If[PrimeQ[3^n - 26], Print[n]], {n, 3, 10000}] PROG (PARI) is(n)=isprime(3^n-26) \\ Charles R Greathouse IV, Feb 17 2017 CROSSREFS Cf. Sequences of numbers n such that 3^n + m is prime:   (m = 2) A051783, (m = -2) A014224, (m = 4) A058958, (m = -4) A058959,   (m = 8) A217136, (m = -8) A217135, (m = 10) A217137, (m = -10) A217347,   (m = 14) A219035, (m = -14) A219038, (m = 16) A205647, (m = -16) A219039,   (m = 20) A219040, (m = -20) A219041, (m = 22) A219042, (m = -22) A219043,   (m = 26) A219044, (m = -26) A219045, (m = 28) A219046, (m = -28) A219047,   (m = 32) A219048, (m = -32) A219049, (m = 34) A219050, (m = -34) A219051. Note that if m is a multiple of 3, 3^n + m is also a multiple of 3 (for n greater than 0), and as such isn't prime. Sequence in context: A007770 A212979 A114961 * A199427 A178508 A123834 Adjacent sequences:  A219042 A219043 A219044 * A219046 A219047 A219048 KEYWORD nonn,more AUTHOR Nicolas M. Perrault, Nov 10 2012 EXTENSIONS a(16)-a(25) from Robert Price, Nov 20 2013 STATUS approved

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Last modified April 15 07:40 EDT 2021. Contains 342975 sequences. (Running on oeis4.)