NEW YORK (REUTERS).- Microsoft Corp co-founder Paul Allen, who has been treated for non-Hodgkin’s lymphoma, said on Thursday he is committing most of his estimated $13.5 billion fortune to philanthropy after his death. Allen follows in the footsteps of former business partner Bill Gates and billionaire investor Warren Buffett, who have both pledged the vast majority of their wealth to philanthropy. Allen, the 37th richest person in the world according to Forbes magazine, co-founded Microsoft in 1975 with Gates and resigned as an executive in 1983 as he overcame a first bout with cancer. He has been involved with philanthropy in the U.S. Pacific Northwest for 20 years, largely through his Paul G. Allen Family Foundation, handing out more than $1 billion in grants and funding for local projects. “Today I also want to announce that my philanthropic efforts will continue after my lifetime,” said Allen in a statement. “I’ve planned for many years now that the majority of my estate wi