Contact Dick Dutton.He has submitted quite a large family tree to Ancestry.com, that contains your Sylvanus.
He appears to have been the son of Sylvanus and Amanda.
Name: Sylvanus BARTLETT Sex: M Birth: 16 DEC 1798 in Plymouth, MA Death: 29 DEC 1849 in New Plymouth, Vinton Co., OH
Note: Sylvanus's second wife and all his children by her are mentioned in a court document filed after his death. That fact that Nancy is not named in the court document and that she was born when Sylvanus would have been 17 make the link suspect. If it weren't for an old family document describing the line, I wouldn't show it here.