fibonacci function
Implementation
List<int> fibonacci(int n) {
if (n == 0) {
return <int>[0];
}
if (n == 1) {
return <int>[0, 1];
}
final List<int> series = fibonacci(n - 1);
series.add(series[series.length - 1] + series[series.length - 2]);
return series;
}