hmm actually formula is a lot simpler....
if u can derive it then it would be good.....otherwise i will post it after some time
Similar to qeustion posted here http://www.targetiit.com/iit-jee-forum/posts/simple-puzzle-11129.html by Nishant sir
Q
I dont want u to calculate no. of triangles..instead derive a general formula for it[1]
check this out
http://www.mathforum.org/library/drmath/view/54894.html
hmm actually formula is a lot simpler....
if u can derive it then it would be good.....otherwise i will post it after some time