n =

( 2 . n ) = x . ( x + 1 )

( 2 . n - 1 ) = x 2

n 2 =

n 3 = =

( n . (n+1) ) =

=

=

=

=

= 1

( n . n! ) = ( x + 1 ) ! -1

sin . sin . sin . ... . sin =