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 A138030 Numbers n such that n remains prime through 8 iterations of function f(x) = 2x + 1. 1
 85864769, 198479579, 305192579, 2400025739, 7606886429, 7755909149, 10378311899, 16744125509, 17029114499, 17117793089, 17574340739, 26089808579, 28889527679, 43390196519, 45424068359, 52179617159, 54293956289, 56838102179, 65639153579, 66655116659 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS FORMULA a(n) == 89 or 329 (mod 330). - John Cerkan, Nov 30 2016 MATHEMATICA 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] &] CROSSREFS Sequence in context: A186922 A185806 A115534 * A104964 A018787 A003825 Adjacent sequences:  A138027 A138028 A138029 * A138031 A138032 A138033 KEYWORD nonn AUTHOR Vladimir Joseph Stephan Orlovsky, May 01 2008 STATUS approved

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Last modified April 11 00:03 EDT 2021. Contains 342877 sequences. (Running on oeis4.)