Add postfix in java 8 way

I need a function which returns a set containing {XXX11, XXX12, XXX13, XXX14, XXX21, ... , XXX43, XXX44} where XXX is a integer argument of the function. What is a elegant way of Java 8 style? I've done in case of prefix is one digit as following:

/**
 * I need to get {<base>11, <base>12, ..., <base>44} but can't...
 * @return {<base>1, <base>2, <base>3, <base>4}
 */
Set<Integer> addOnlyOnePrefix(int base){
  return IntStream.range(1, 4).map(prefix -> base*10 + prefix)
      .boxed().collect(Collectors.toSet());
}
Jon Skeet
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The simplest way is probably to just generate 16 values:

Set<Integer> addOnlyTwoPrefixes(int base) {
  return IntStream.range(0, 16)
      .map(prefix ->
          base * 100 +             // Leading digits
          10 + 10 * (prefix / 4) + // Penultimate digit
          1 + (prefix % 4))        // Last digit
      .boxed()
      .collect(Collectors.toSet());
}

The 10+ and 1+ are to take account of prefix / 4 and prefix % 4 being in the range 0-3 rather than 1-4.

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