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A243300
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Numbers k such that k^6 - k^5 - k^4 - k^3 - k^2 - k - 1 is prime.
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2
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4, 5, 7, 9, 17, 30, 37, 39, 42, 62, 69, 72, 79, 82, 85, 90, 92, 95, 99, 104, 110, 157, 170, 175, 177, 182, 187, 194, 195, 215, 217, 220, 234, 239, 240, 242, 255, 262, 269, 272, 277, 319, 334, 339, 342, 344, 359, 365, 369, 370, 374, 377, 387, 392, 400, 417, 419, 449
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OFFSET
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1,1
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LINKS
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EXAMPLE
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4^6 - 4^5 - 4^4 - 4^3 - 4^2 - 4 - 1 = 2731 is prime. Thus 4 is a member of this sequence.
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MATHEMATICA
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Rest@ Select[Range@ 450, Function[n, PrimeQ[Fold[#1 - n^#2 &, n^6, Range@ 5] - 1]]] (* Michael De Vlieger, Apr 03 2017 *)
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PROG
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(Python)
import sympy
from sympy import isprime
{print(n, end=', ') for n in range(10**3) if isprime(n**6-n**5-n**4-n**3-n**2-n-1)}
(PARI) for(n=1, 10^3, if(ispseudoprime(n^6-sum(i=0, 5, n^i)), print1(n, ", ")))
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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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