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A243300 Numbers k such that k^6 - k^5 - k^4 - k^3 - k^2 - k - 1 is prime. 2
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 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

John Cerkan, Table of n, a(n) for n = 1..10000

EXAMPLE

4^6 - 4^5 - 4^4 - 4^3 - 4^2 - 4 - 1 = 2731 is prime. Thus 4 is a member of this sequence.

MATHEMATICA

Rest@ Select[Range@ 450, Function[n, PrimeQ[Fold[#1 - n^#2 &, n^6, Range@ 5] - 1]]] (* Michael De Vlieger, Apr 03 2017 *)

PROG

(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, ", ")))

CROSSREFS

Sequence in context: A035264 A234257 A278335 * A231575 A335001 A153085

Adjacent sequences:  A243297 A243298 A243299 * A243301 A243302 A243303

KEYWORD

nonn

AUTHOR

Derek Orr, Jun 02 2014

STATUS

approved

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Last modified July 4 04:47 EDT 2022. Contains 355064 sequences. (Running on oeis4.)