A convicted sex offender who had been living in a Pittsfield nursing home has pleaded not guilty to a charge of failing to register as a sex offender. According to the Berkshire Eagle, police said Thomas Dewey, 59, failed to inform law enforcement officials of his residence, which is required of sex offenders. Police also say Dewey misled them when they tried to verify his whereabouts. Dewey, considered by the state to be at a ‘‘high risk’’ to reoffend, was convicted in 1995 of child rape with force and indecent assault and battery on a person under 15. His lawyer did not immediately return a call on Sunday seeking comment. Dewey was released Thursday on his own recognizance.