VOOZH about

URL: https://oeis.org/A339519

⇱ A339519 - OEIS

login
A339519
Odd composite integers m such that A087130(2*m-J(m,29)) == 5*J(m,29) (mod m), where J(m,29) is the Jacobi symbol.
3
9, 15, 27, 39, 45, 91, 117, 121, 135, 143, 195, 287, 351, 507, 585, 741, 1521, 1547, 1573, 1755, 1935, 2015, 2067, 2535, 2601, 3157, 3227, 3445, 3505, 3519, 3731, 4563, 4879, 4921, 6201, 6273, 6543, 6591, 6721, 7605, 7803, 8099, 10335, 10377, 10403, 10515
OFFSET
1,1
COMMENTS
The generalized Pell-Lucas sequences of integer parameters (a,b) defined by V(m+2)=a*V(m+1)-b*V(m) and V(0)=2, V(1)=a, satisfy V(k*p-J(p,D)) == V(k-1)*J(p,D) (mod p) whenever p is prime, k is a positive integer, b=-1 and D=a^2+4.
The composite integers m with the property V(k*m-J(m,D)) == V(k-1)*J(m,D) (mod m) are called generalized Pell-Lucas pseudoprimes of level k- and parameter a.
Here b=-1, a=5, D=29 and k=2, while V(m) recovers A087130(m).
REFERENCES
D. Andrica, O. Bagdasar, Recurrent Sequences: Key Results, Applications and Problems. Springer, 2020.
D. Andrica, O. Bagdasar, On some new arithmetic properties of the generalized Lucas sequences, Mediterr. J. Math. (to appear, 2021).
D. Andrica, O. Bagdasar, On generalized pseudoprimality of level k (submitted).
LINKS
Dorin Andrica, Vlad Crişan, and Fawzi Al-Thukair, On Fibonacci and Lucas sequences modulo a prime and primality testing, Arab Journal of Mathematical Sciences, 24(1), 9-15 (2018).
MATHEMATICA
Select[Range[3, 20000, 2], CoprimeQ[#, 29] && CompositeQ[#] && Divisible[LucasL[2*# - JacobiSymbol[#, 29], 5] - 5*JacobiSymbol[#, 29], #] &]
CROSSREFS
Cf. A087130, A071904, A339127 (a=5, b=-1, k=1).
Cf. A339517 (a=1, b=-1), A339518 (a=3, b=-1), A339520 (a=7, b=-1).
Sequence in context: A013569 A129401 A164385 * A258813 A046353 A340095
KEYWORD
nonn
AUTHOR
Ovidiu Bagdasar, Dec 07 2020
STATUS
approved