with javascript_semantics
include mpfr.e
procedure repunit(mpz z, integer n, base=10)
    mpz_set_si(z,0)
    for i=1 to n do
        mpz_mul_si(z,z,base)
        mpz_add_si(z,z,1)
    end for
end procedure

atom t0 = time()
constant {limit,blimit} = iff(platform()=JS?{400,16} -- 1.2s
                                           :{1000,16}) -- 22s
--                                         :{1000,36}) -- 1 min 35s
--                                         :{2700,16}) -- 9 min 30s
--                                         :{2700,40}) -- 52 minutes and 30s
sequence primes = get_primes_le(limit)
mpz z = mpz_init()
for base=2 to blimit do
    sequence rprimes = {}
    for i=1 to length(primes) do
        integer p = primes[i]
        repunit(z,p,base)
        if mpz_prime(z) then
            rprimes &= p
        end if
    end for
    printf(1,"Base %2d: %v\n", {base, rprimes})
end for
?elapsed(time()-t0)