Chebyshev-like bias conjecture for entry points of primes in Lucas sequences

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Let UU be a Lucas sequence with discriminant DD, and let zU(p)z_U(p) be the entry point of a prime pp in UU, with zU(p)=∞z_U(p)=\infty for primes dividing QQ but not PP. Define

RU={p∈P:(Dp)=1},NU={p∈P:(Dp)=−1}.R_U=\left\{p\in\mathbb{P}:\left(\frac{D}{p}\right)=1\right\},\qquad N_U=\left\{p\in\mathbb{P}:\left(\frac{D}{p}\right)=-1\right\}.

For x>0x>0, set ZU(x)={p∈P:zU(p)≤x}Z_U(x)=\{p\in\mathbb{P}:z_U(p)\leq x\}, ZUR(x)=ZU(x)∩RUZ_U^R(x)=Z_U(x)\cap R_U, and ZUN(x)=ZU(x)∩NUZ_U^N(x)=Z_U(x)\cap N_U, and define

BU(x)=#{1≤n≤x:#ZUN(n)<#ZUR(n)}.B_U(x)=\#\left\{1\leq n\leq x:\#Z_U^N(n)<\#Z_U^R(n)\right\}.

Chebyshev-like bias conjecture. (Weak) If UU is a regular Lucas sequence with D>0D>0, then

BU(x)x⟶x→∞1.\frac{B_U(x)}{x}\underset{x\rightarrow\infty}{\longrightarrow}1.

(Strong) If UU is a regular Lucas sequence with D>0D>0, then #ZUN(n)<#ZUR(n)\#Z_U^N(n)<\#Z_U^R(n) for all but finitely many n≥1n\geq1; in particular, for the Fibonacci sequence FF,

#ZFN(n)<#ZFR(n)\#Z_F^N(n)<\#Z_F^R(n)

for all n>36n>36. This conjectures a strong Chebyshev-like bias favoring primes with Legendre symbol (Dp)=1\left(\frac{D}{p}\right)=1 among the entry points of primes in real regular Lucas sequences. The weak and strong forms remain open in the supplied text.

References

Primary source

Tyler Ross, Zhongyan Shen and Tianxin Cai, “Cyclotomic Congruences and Lucas Sequences”, arXiv:2512.03468 (2026).

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