Can you determine the next number in the below sequence?

$1.0 , 4.0 , 6.9 , 9.0 , 10.8 , 12.0 , 14.0 , 16.0 , ?$

Bonus: Determine the next number that comes after '?'

Note: I'll post some hints if nobody gets the answer.

Hint #1: You won't get the relationship between the numbers by calculating.

Hint #2: These numbers have some relationship with science.

  • $\begingroup$ Too broad; too many answers. Voted to close. $\endgroup$
    – warspyking
    Jan 3, 2015 at 14:27
  • 2
    $\begingroup$ The problem with this is that it's just a sequence. We could throw guesses at the wall all day and by the end be no closer to a solution. This type of puzzle is generally disliked on puzzling.SE, and moreover disliked as a whole. $\endgroup$ Jan 3, 2015 at 14:48
  • 4
    $\begingroup$ From seeing the answer: This is a puzzle where you either recognize the pattern or you don't. You can't get anywhere by thinking by about it. $\endgroup$
    – xnor
    Jan 3, 2015 at 16:32
  • $\begingroup$ @xnor And it won't even be on OEIS (I think) because it isn't an integer sequence... $\endgroup$
    – mdc32
    Jan 3, 2015 at 17:26
  • 1
    $\begingroup$ @RobWatts Never mind. oeis.org/… but you'd have to round $\endgroup$
    – mdc32
    Jan 3, 2015 at 21:49

1 Answer 1


The numbers represent

Atomic weights

The next 5 numbers are

19.0, 20.2, 23.0, 24.3, and 27.0


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