func jacobsthal(n) {
    lucasU(1, -2, n)
}

func lucas_jacobsthal(n) {
    lucasV(1, -2, n)
}

say "First 30 Jacobsthal numbers:"
say 30.of(jacobsthal)

say "\nFirst 30 Jacobsthal-Lucas numbers:"
say 30.of(lucas_jacobsthal)

say "\nFirst 20 Jacobsthal oblong numbers:"
say 21.of(jacobsthal).cons(2, {|a,b| a * b })

say "\nFirst 20 Jacobsthal primes:";
say (1..Inf -> lazy.map(jacobsthal).grep{.is_prime}.first(20))