"Harlan Grove" wrote in message
ups.com...
Gauss's formula was simpler that Phillips's formula.

LOL. I know it is. I knew the formula, just made a hash of it as I forgot
it was as true for an odd final n umber as it was for an even.

Or

=(A2*(A2+1)-(A1-1)*A1)/2


Yeah, that's nicer.