Posted by Jonathan Burros on September 11, 2002 at 11:35:24:
In Reply to: Terminology question - for the professors posted by Joel on September 11, 2002 at 10:32:04:
: Is a Sum statement properly termed a "function"
: so that EITHER of the following:
: f(n) = n(n+1)/2
: and
: f(n) = Sum[from n=1 to n]n
: BY ITSELF would be correctly considered a function that defines the series {1,3,6,10,15...} ?
: The former, of course, is a quadratic function. What is the latter? Is it a propositional function?
You wrote the latter
f(n) = Sum[from n=1 to n]n
wrong
It should be
f(n) = Sum[from j=1 to n]j
Then f(n)= n(n+1)/2
Yes f(n)=n(n+1)/2 defines the series
{1,3,6,10,15...}