This is an old snippet I wrote years ago. It return the sum of a defined series of integers. Also, when pulling the description from the snippet to this box, I was too lazy to delete the semicolons. Sorry.

Changed from the original:
Addition of credit to MPDreamz for doing optimization to my snippet, and adding (now Illogic) next to my old nick.

;---Usage---
;
;$gaussa(n1,n2,n3) -- (n3 is optional)
;
;n1 and n2 define the beginning and end of a numeric series, and n3
;can be used to define the increase from number to number (if the increase
;is greater than 1.)
;
;e.g.,
;/echo Code: $gaussa(1,5,2) will return 9, since from 1 to 5, and
;increasing by 2 each time equals 9. (1 + 3 + 5)
;
;/echo Code: $gaussa(1,5) will return 15, because (1 + 2 + 3 + 4 + 5) = 15.
;
;Not specifying n3 will automatically set the increase between numbers to 1.
;If (n2 - n1) is not a multiple of n3, the script will return null.

;Gauss 1.0
;By Lime (now Illogic)
;Code Optimization by MPDreamz

alias gaussa {
  if ($3 \\ $calc($1 - $2)) return
  var %x $1 , %y $1
  while (%x < $2) {
    inc %x $3
    inc %y %x
  }
  return %y
}