2018杭电多校day1_G - Chiaki Sequence Revisited HDU - 6308
Chiakiisinterestedinaninfinitesequencea1,a2,a3,...a1,a2,a3,...,whichisdefinedasfollows:an={1an−an−1+an−1−an−2n=1,2n≥3an={1n=1,2an−an−1+an−1−an−2n≥3Chiakiwouldliketoknowthesumofthefirstnntermsofthesequ