Funny Numbers, Sequentially

It's a shame that with literally an infinite amount of numbers, there are only 6 that are funny.
  1. 69
  2. 420
  3. 666
  4. 80085
  5. 5318008
    Upside down, on a calculator
  6. 8675309
  7. Honorable mentions
  8. -69
  9. -420
  10. -666
  11. -80085
  12. -5318008
    Upside down, on a calculator
  13. -8675309