Truman was before Eisenhower, so that makes it fourteen.
https://www.msn.com/en-gb/health/other/queen-elizabeth-meets-president-truman-in-1951/vi-AA11C58S?category=foryou
But no LBJ makes it back down to 13. It wasn’t the number of Presidents that caught my eye.
Just that it had to be him who was the last one.