Formal power series extend the notion of a power series by removing the requirement for convergance[?]. Thus they have the same form as a power serries, but a more abstract interpretation which can be applied more generally.
... 1981)
June 2 - Johnny Weissmuller, American swimmer and actor
July 12 - Deng Xiaoping, Chinese politician and leader
July 13 - Pablo Neruda, poet
August 28 - ...