The increasing sequence 1,3,4,9,10,12,13,… consists of all those positive integers which are powers of 3 or sums of distinct powers of 3. Find the $$100^{th}$$ term of this sequenc(where 1 is the $$1^{st}$$ term, 3 is the $$2^{nd}$$ term, and so on).

(第四届AIME1986 第7题)