I bought Nano awhile back and stored it on the Nano site. I believe it may have been Raiblocks back then, because I wrote down a seed that has 24 letters. The site isn't active and I have tried importing my 24 letter seed in Natrium but it says "invalid seed". Am I doing something wrong? Most people have suggested I should have a 64 character seed, but I'm certain I was not given a 64 character seed or I would have written it down. I was very meticulous with my records. Any advice would be a huge help.