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A236171 Numbers n such that n^2 - n - 1, n^3 - n - 1, and n^4 - n - 1 are all prime. 1
4, 9, 11, 16, 55, 60, 71, 189, 361, 450, 469, 669, 1261, 1351, 1490, 1591, 2101, 2254, 2396, 2594, 3774, 3866, 4011, 5375, 5551, 5840, 6070, 7336, 7545, 7666, 7735, 8105, 8255, 9825, 10525, 11621, 12100, 13084, 13454 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..39.

EXAMPLE

3866^2 - 3866 - 1, 3866^3 - 3866 - 1, and 3866^4 - 3866 - 1 are all prime, so 3866 is a member of this sequence.

PROG

(Python)

import sympy

from sympy import isprime

{print(n) for n in range(10**5) if isprime(n**2-n-1) and isprime(n**3-n-1) and isprime(n**4-n-1)}

(PARI)

s=[]; for(n=1, 20000, if(isprime(n^2-n-1) && isprime(n^3-n-1) && isprime(n^4-n-1), s=concat(s, n))); s \\ Colin Barker, Jan 20 2014

CROSSREFS

Cf. A002328, A126421, A126424.

Sequence in context: A190559 A316621 A212017 * A312838 A312839 A312840

Adjacent sequences:  A236168 A236169 A236170 * A236172 A236173 A236174

KEYWORD

nonn

AUTHOR

Derek Orr, Jan 19 2014

STATUS

approved

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Last modified August 22 07:40 EDT 2019. Contains 326172 sequences. (Running on oeis4.)