function to calculate the coefficients of ( x - 1 ) ^ n - ( x ^ n - 1 ) with the help of Pascal 's triangle .
def coef ( n ) : NEW_LINE INDENT c [ 0 ] = 1 ; NEW_LINE for i in range ( n ) : NEW_LINE INDENT c [ 1 + i ] = 1 ; NEW_LINE for j in range ( i , 0 , - 1 ) : NEW_LINE INDENT c [ j ] = c [ j - 1 ] - c [ j ] ; NEW_LINE DEDENT c [ 0 ] = - c [ 0 ] ; NEW_LINE DEDENT DEDENT