Write the An'th term sequence for 0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, ....?

Question

i cant figure it out it's killing me
i tried An = (n-1)(|n|-2)
nothing works :(

Answer 1

You are looking for this expression, where n begins with 1:

(1/2)(n - (1/2) + (1/2)(-1)^n)

Try it out. You'll get 0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, etc.

Answer 2

Try this :

A ( n ) = ( n + 1)/2 when n is odd.
A ( n ) = ( n )/2 when n is even.

:)