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A138030
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Numbers n such that n remains prime through 8 iterations of function f(x) = 2x + 1.
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1
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85864769, 198479579, 305192579, 2400025739, 7606886429, 7755909149, 10378311899, 16744125509, 17029114499, 17117793089, 17574340739, 26089808579, 28889527679, 43390196519, 45424068359, 52179617159, 54293956289, 56838102179, 65639153579, 66655116659
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OFFSET
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1,1
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LINKS
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FORMULA
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a(n) == 89 or 329 (mod 330). - John Cerkan, Nov 30 2016
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MATHEMATICA
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Select[Prime[Range[10^8]], PrimeQ[a1=2*#+1]&&PrimeQ[a2=2*a1+1]&&PrimeQ[a3=2*a2+1]&&PrimeQ[a4=2*a3+1]&&PrimeQ[a5=2*a4+1]&&PrimeQ[a6=2*a5+1]&&PrimeQ[a7=2*a6+1]&&PrimeQ[a8=2*a7+1] &]
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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