( ) ( ) ( ) = ( + 1)(2 + 1) 6 ( ) ( ) (3) = = 0 + 1 + 2 + 3 = 0 + 1 + 4 + 9 = 14 3(3 + 1)(2 3 + 1) 3 4 7 = = 14 6 6 = = ( ) =0 ( ) (0) = = =0 =0 0(0 + 1)(2 0 + 1) =0 6 = ( ) ( ) = ( + 1)(2 + 1) 6 ( ) ( + 1) = ( + 1){( + 1) + 1}{2( + 1) + 1} 6 ( ) ( ) = ( + 1) = ( + 1)(2 + 1) 6 ( + 1){( + 1) + 1}{2( + 1) + 1} 6 ( ) ( + 1) ( ) ( + 1) ( + 1) = = 0 +1 +2 +....+ = [0 + 1 + 2 + ... . + = + ( + 1) + +( + 1) . + ( + 1) = ( ) + ( + 1) ( ) ( + 1) ( ) ( + 1) ,