public static int numberOfTriangles ( int n ) {
  int [ ] answer = new int [ n + 1 ] ;
  answer [ 0 ] = 1 ;
  for ( int i = 1 ;
  i <= n ;
  i ++ ) answer [ i ] = answer [ i - 1 ] * 3 + 2 ;
  return answer [ n ] ;
}

public static int numberOfTriangles ( int n ) { int [ ] answer = new int [ n + 1 ] ; answer [ 0 ] = 1 ; for ( int i = 1 ; i <= n ; i ++ ) answer [ i ] = answer [ i - 1 ] * 3 + 2 ; return answer [ n ] ; }
(method_declaration (modifiers) type: (integral_type) name: (identifier) parameters: (formal_parameters (formal_parameter type: (integral_type) name: (identifier))) body: (block (local_variable_declaration type: (array_type element: (integral_type) dimensions: (dimensions)) declarator: (variable_declarator name: (identifier) value: (array_creation_expression type: (integral_type) dimensions: (dimensions_expr (binary_expression left: (identifier) right: (decimal_integer_literal)))))) (expression_statement (assignment_expression left: (array_access array: (identifier) index: (decimal_integer_literal)) right: (decimal_integer_literal))) (for_statement init: (local_variable_declaration type: (integral_type) declarator: (variable_declarator name: (identifier) value: (decimal_integer_literal))) condition: (binary_expression left: (identifier) right: (identifier)) update: (update_expression (identifier)) body: (expression_statement (assignment_expression left: (array_access array: (identifier) index: (identifier)) right: (binary_expression left: (binary_expression left: (array_access array: (identifier) index: (binary_expression left: (identifier) right: (decimal_integer_literal))) right: (decimal_integer_literal)) right: (decimal_integer_literal))))) (return_statement (array_access array: (identifier) index: (identifier)))))