**Source:**

Asked to me by Amol Sahasrabudhe (IITB 2004 Alumnus, Worked at Morgan Stanley Quant Division, Deutsche Bank)

**Problem:**

You are given *2n* numbers ( *1* to *n* and *1* to *n* ). You have to arrange these numbers in a sequence such that between any two *i*`s, there exists exactly *i-1* numbers. Is it possible for all *n*? If no, what are the values of *n *for which this is possible?

**Disclaimer:**

I have not been able to solve it. Sudhanshu Tungare (IITB 2008 EE Alumnus, Morgan Stanley) claims to have a solution. Cheers!

**Update** (November 1, 2011):

Part solution posted by Nishant Totla (CSE IITB Senior Undergraduate), Richie and Sarat in comments! Complete solution posted by Siddhant Agarwal (EE IITB Alumnus, CMI Grad student) in comments! Thanks a ton.