Dynamic Column cell reference with autofill (opens in new tab)

Hi,I want to increase the column reference in a formula by 2 columns as it is copied across columns.So in Column A the formula is =SUM(D3:E3)When I fill this across Column B I want the formula to be =SUM(F3:G3)I have experimented with the INDEX and COLUMN functions but not been able to get the intended result.