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A106281
Primes p such that the polynomial x^5-x^4-x^3-x^2-x-1 mod p has 5 distinct zeros.
4
691, 733, 3163, 4259, 4397, 5419, 6637, 6733, 8009, 8311, 9803, 11731, 14923, 17291, 20627, 20873, 22777, 25111, 26339, 27947, 29339, 29389, 29527, 29917, 34123, 34421, 34739, 34757, 36527, 36809, 38783, 40433, 40531, 41131, 42859, 43049
OFFSET
1,1
COMMENTS
This polynomial is the characteristic polynomial of the Fibonacci and Lucas 5-step sequences, A001591 and A074048. The periods of the sequences A001591(k) mod p and A074048(k) mod p have length less than p.
LINKS
Eric Weisstein's World of Mathematics, Fibonacci n-Step Number.
MATHEMATICA
t=Table[p=Prime[n]; cnt=0; Do[If[Mod[x^5-x^4-x^3-x^2-x-1, p]==0, cnt++ ], {x, 0, p-1}]; cnt, {n, 5000}]; Prime[Flatten[Position[t, 5]]]
PROG
(Python)
from itertools import islice
from sympy import Poly, nextprime
from sympy.abc import x
def A106281_gen(): # generator of terms
p = 2
while True:
if len(Poly(x*(x*(x*(x*(x-1)-1)-1)-1)-1, x, modulus=p).ground_roots())==5:
yield p
p = nextprime(p)
A106281_list = list(islice(A106281_gen(), 20)) # Chai Wah Wu, Mar 14 2024
CROSSREFS
Cf. A106278 (number of distinct zeros of x^5-x^4-x^3-x^2-x-1 mod prime(n)), A106298, A106304 (period of Lucas and Fibonacci 5-step mod prime(n)).
Sequence in context: A029825 A180320 A159283 * A127341 A135316 A160500
KEYWORD
nonn
AUTHOR
T. D. Noe, May 02 2005
STATUS
approved