[Perfect number][1] is a positive integer that is equal to the sum of its proper divisors. The smallest perfect number is 6, which is the sum of 1, 2, and 3.

Is there a sequence of numbers which are equal to the sum of its proper divisors **excluding itself as well as 1**?

If yes, what are they called? Name first few numbers in the sequence.

Is there a general formula for them?

Please provide with some link to read more.

  [1]: https://www.britannica.com/topic/perfect-number