func f(n) {
    n == 0 ? 1 : n - m(f(n-1))
}
and m(n) {
    n == 0 ? 0 : n - f(m(n-1))
}

print( (0..20).Map(i => f(i)).ToArray() )
print( (0..20).Map(i => m(i)).ToArray() )