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A243297 Numbers k such that k^8 - k^7 - k^6 - k^5 - k^4 - k^3 - k^2 - k - 1 is prime. 2
4, 5, 18, 23, 24, 25, 39, 41, 49, 61, 68, 73, 100, 102, 103, 109, 111, 114, 125, 140, 150, 157, 158, 167, 181, 210, 228, 242, 245, 259, 282, 286, 287, 290, 294, 299, 300, 303, 307, 311, 315, 325, 341, 347, 364, 367, 371, 385, 390, 395, 403, 406, 415, 430, 437, 441, 444 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

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

EXAMPLE

4^8 - 4^7 - 4^6 - 4^5 - 4^4 - 4^3 - 4^2 - 4^1 - 1 = 43691 is prime. Thus 4 is a term.

MATHEMATICA

Rest@ Select[Range@ 450, Function[n, PrimeQ[Fold[#1 - n^#2 &, n^8, Range@ 7] - 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**8-n**7-n**6-n**5-n**4-n**3-n**2-n-1)}

(PARI) for(n=1, 10^3, if(ispseudoprime(n^8-sum(i=0, 7, n^i)), print1(n, ", ")))

CROSSREFS

Cf. A000040.

Sequence in context: A134750 A051949 A275961 * A026902 A026755 A243120

Adjacent sequences:  A243294 A243295 A243296 * A243298 A243299 A243300

KEYWORD

nonn

AUTHOR

Derek Orr, Jun 02 2014

STATUS

approved

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Last modified September 19 00:22 EDT 2021. Contains 347549 sequences. (Running on oeis4.)