If the number of positive integral solutions of x_1 +x_2+x_3=n be denoted by P_n then ∣∣ ∣∣PnPn+1Pn+2Pn+1Pn+2Pn+3Pn+2Pn+3Pn+4∣∣ ∣∣=
0
1
- 1
- 8
∣∣ ∣ ∣∣nC2n+1C2n+2C2n+1C2n+2C2n+3C2n+2C2n+3C2n+4C2∣∣ ∣ ∣∣=−1