starship-design: Help with formula

[Zenon Kulpa <zkulpa@zmit1.ippt.gov.pl>]

Please, I have lost it somewhere, no time to search or derive,
what is the formula for Earth time & crew time
in the (one-way) flight with constant acceleration = 1g 
(half way +, half way - ) depending on the distance (in ly)?

Thanks, 

-- Zenon