Prime RSA number generator (RSA-4096)

import random
g = random.SystemRandom()
lprimes= [2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61,67,73,79,83,89,97,101,103,107,109,113,127,131,137,139,149,151,157,163,167,173,179,181,191,193,197,199, 211, 223, 227, 229, 233, 239, 241, 251, 257, 263, 269, 271, 277, 281, 283, 293, 307, 311, 313, 317, 331, 337, 347, 349, 353, 359, 367, 373, 379, 383, 389, 397, 401, 409, 419, 421, 431, 433, 439, 443, 449, 457, 461, 463, 467, 479, 487, 491, 499, 503, 509, 521, 523, 541]
def decomp(n):
    q = n-1
    s = 0
    while not q&1:
            s+=1
            q= q//2
    return s,q
def trial(n):
    for i in lprimes:
        x= n%i
        if not x:
            return False
    return True
def mrt(n,t=7):
    if n&1:
        n=n
    else:
        n=n+1
    if trial(n):
        s,q = decomp(n)
        for _ in range(t):
                a=random.randrange(2,n-1)

                y = pow(a,q,n)
                if y == 1 or y == -1:
                        return n
                else:
                        if s>1:
                            for i in range(1,s):
                                if pow(a,(2**i)*q,n) == -1:
                                        return n
        return False
if __name__ == "__main__":
    while 1:
        a = random.randrange(10**255,10**256)
        x = mrt(a)
        if x:
            print(x)