Levi Strauss & Co., the 145-year-old company credited with creating the first pair of blue jeans, is planning an initial public offering, people with knowledge of the matter said. Levi’s is looking to raise between $600 million and $800 million and targeting the first quarter of 2019 to go public, said the people, who asked not to be named discussing confidential deal details. The company is aiming to debut with a valuation upward of $5 billion, the people said. The San Francisco-based company has tapped Goldman Sachs and J.P. Morgan to manage the deal, although the timing and size of the offering could change, the people said.