Neil Sloane wanted to know which terms I was "sure of". Well, until I have a rigorous bound for accumulated roundoff error, which I do not, I'm not sure of any term. However, the reason I printed those terms with both integer and float forms, was to enable the reader to estimate how much roundoff error there is. (Such an estimate is not 100% certain, sorry.) I think every determinant of an NxN sign matrix, N<=26, should be exact. I think every number I gave, no matter how large the matrix, ought to be good for 9 significant figures (Sloane may not like approximate answers, but he can get them if he wants). [I stopped trying to enter numbers into the OEIS myself quite a while ago because it was just too damn annoying to use, and plus to add insult to injury it had blown away my login account but nevertheless insisted I use it.]