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On the primitive divisors of the recurrent sequence un + 1= (4 cos2(2 π/ 7) − 1) un−un − 1 with applications to group theory. / Vsemirnov, Maxim.
In: Science China Mathematics, Vol. 61, No. 11, 01.11.2018, p. 2101-2110.Research output: Contribution to journal › Article › peer-review
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TY - JOUR
T1 - On the primitive divisors of the recurrent sequence un + 1= (4 cos2(2 π/ 7) − 1) un−un − 1 with applications to group theory
AU - Vsemirnov, Maxim
PY - 2018/11/1
Y1 - 2018/11/1
N2 - Consider the sequence of algebraic integers un given by the starting values u0 = 0, u1 = 1 and the recurrence un + 1= (4 cos2(2 π/ 7) − 1) un−un − 1. We prove that for any n ∉ {1, 2, 3, 5, 8, 12, 18, 28, 30} the n-th term of the sequence has a primitive divisor in Z[2cos(2π/7)]. As a consequence we deduce that for any suffciently large n there exists a prime power q such that the group PSL2(q) can be generated by a pair x, y with x2= y3= (xy) 7= 1 and the order of the commutator [x, y] is exactly n. The latter result answers in affrmative a question of Holt and Plesken.
AB - Consider the sequence of algebraic integers un given by the starting values u0 = 0, u1 = 1 and the recurrence un + 1= (4 cos2(2 π/ 7) − 1) un−un − 1. We prove that for any n ∉ {1, 2, 3, 5, 8, 12, 18, 28, 30} the n-th term of the sequence has a primitive divisor in Z[2cos(2π/7)]. As a consequence we deduce that for any suffciently large n there exists a prime power q such that the group PSL2(q) can be generated by a pair x, y with x2= y3= (xy) 7= 1 and the order of the commutator [x, y] is exactly n. The latter result answers in affrmative a question of Holt and Plesken.
KW - 11B37
KW - 20F05
KW - Hurwitz groups
KW - primitive divisors
KW - recurrent sequences
KW - TRIANGLE GROUPS
KW - LUCAS
KW - QUOTIENTS
KW - HURWITZ GROUPS
UR - http://www.scopus.com/inward/record.url?scp=85052912448&partnerID=8YFLogxK
U2 - 10.1007/s11425-017-9347-3
DO - 10.1007/s11425-017-9347-3
M3 - Article
AN - SCOPUS:85052912448
VL - 61
SP - 2101
EP - 2110
JO - Science China Mathematics
JF - Science China Mathematics
SN - 1674-7283
IS - 11
ER -
ID: 36947097