OEIS A014445 - Even Fibonacci numbers; or, Fibonacci(3*n).

main.dart

/// OEIS A014445 - Even Fibonacci numbers; or, Fibonacci(3*n).
/// https://oeis.org/A014445
/// https://oeis.org/A014445/list

void main() => print(evenFibonacci().take(26));

Iterable<int> evenFibonacci() sync* {
  int a = 0, b = 2;
  
  while (true) {
    yield a;
    
    int temp = a;
    
    a = b;
    b = temp + 4 * b;
  }
}