•10050010050

[phpBB Debug] PHP Warning: in file [ROOT]/phpbb/session.php on line 580: sizeof(): Parameter must be an array or an object that implements Countable
[phpBB Debug] PHP Warning: in file [ROOT]/phpbb/session.php on line 636: sizeof(): Parameter must be an array or an object that implements Countable
•10050010050

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10050010050

Posted: Mon Oct 16, 2017 7:00 pm

by ada

$2^1+2^2+2^3+2^4+\dotsb+2^n=2^{n+1}-2$