10 28.11

extension on int {
  List<int> getDivs(final bool Function(int) predicate) {
    final divs = List<int>.empty(growable: true);
    for (int i = 1; i * i <= this; i++) {
      if (this % i == 0) {
        if (predicate(i)) {
          divs.add(i);
        }

        if (i * i < this && predicate(this ~/ i)) {
          divs.add(this ~/ i);
        }
      }
    }

    return divs;
  }

  bool get isSimple {
    for (int i = 2; i * i <= this; i++) {
      if (this % i == 0) {
        return false;
      }
    }

    return true;
  }
}

extension on List<int> {
  List<int> sortAndGet() {
    sort();
    return this;
  }
}

extension IntIterableExt on Iterable<int> {
  static Iterable<int> createRange(final int startInclusive, final int endExclusive) =>
      Iterable.generate(endExclusive - startInclusive + 1, (x) => x + startInclusive);
}

extension IterableExt<T> on Iterable<T> {
  Iterable<T> withStep(final int step) {
    final list = List<T>.empty(growable: true);
    final thisList = toList();

    for (int i = 0; i < length; i += step) {
      list.add(thisList[i]);
    }

    return list;
  }

  void forEachIndexed(void Function(int, T) action) {
    final iter = iterator;

    for (int i = 0; i < length; i++) {
      iter.moveNext();
      action(i, iter.current);
    }
  }
}

void main(final List<String> arguments) =>
    IntIterableExt.createRange(2532000, 2532160)
        .where((element) => element.isSimple)
        .withStep(3)
        .forEachIndexed((ind, e) => print('${(ind + 1) + ind * 2} $e'));