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A127587
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Smallest nonnegative integer k such that (k+1)*2^n-1 is prime.
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13
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2, 1, 0, 0, 1, 0, 1, 0, 4, 6, 4, 2, 1, 0, 4, 3, 1, 0, 1, 0, 13, 6, 25, 12, 38, 21, 10, 15, 7, 3, 1, 0, 4, 5, 2, 23, 11, 5, 2, 24, 23, 11, 5, 2, 13, 6, 19, 9, 4, 18, 10, 20, 19, 9, 4, 2, 31, 15, 7, 3, 1, 0, 11, 5, 2, 66, 62, 42, 62, 39, 19, 9, 4, 14, 11, 5, 2, 54, 46, 29, 14, 29, 14, 63, 31, 15, 7
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OFFSET
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0,1
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COMMENTS
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The associated prime number list is (k+1)*2^n-1 = 2,3,3,7,31,31,127,127,1279,3583,5119,6143,... for n=0,1,2,3,4,... - R. J. Mathar, Jan 22 2007
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LINKS
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FORMULA
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MAPLE
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A127587 := proc(n) local k; k:=0 ; while true do if isprime( (k+1)*2^n-1) then RETURN(k) ; fi ; k := k+1 ; od ; end: for n from 0 to 100 do printf("%d, ", A127587(n)) ; od ; # R. J. Mathar, Jan 22 2007
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MATHEMATICA
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a = {}; Do[k = 0; While[ ! PrimeQ[k 2^n + 2^n - 1], k++ ]; AppendTo[a, k], {n, 0, 50}]; a
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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