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 A261579 Numbers m such that (4^m + 23) / 3 is prime. 1
 2, 3, 5, 6, 27, 47, 66, 77, 83, 105, 197, 231, 293, 702, 1692, 3021, 6270, 6897, 7733, 14537, 15797, 21083, 21276, 28817, 65430, 111231, 137405, 141017, 185225 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS a(30) > 450,000. - Robert Price, Oct 04 2018 LINKS EXAMPLE 2 is in the sequence because (4^2 + 23)/3 = 13 is prime. 3 is in the sequence because (4^3 + 23)/3 = 29 is prime. MATHEMATICA Select[Range[0, 5000], PrimeQ[(4^# + 23)/3] &] PROG (MAGMA) [n: n in [0..1500] | IsPrime((4^n+23) div 3)]; CROSSREFS Cf. similar sequences listed in A261539. Sequence in context: A131599 A263650 A076384 * A270517 A124648 A093339 Adjacent sequences:  A261576 A261577 A261578 * A261580 A261581 A261582 KEYWORD nonn,more AUTHOR Vincenzo Librandi, Aug 27 2015 EXTENSIONS a(17)-a(28) from Robert Price, Feb 01 2017 a(29) from Robert Price, Oct 04 2018 STATUS approved

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Last modified December 7 20:33 EST 2019. Contains 329849 sequences. (Running on oeis4.)