Nope, so far time Warner makes you get a cable+hbo subscription to watch HBO Go
You can pirate it, but then you're a pirate, only without the boat and sword and "where has all the rum gone" and really a few seasons' of True Blood isn't much treasure for a pirate. Also your internet provider can cancel or throttle your service.
Even on a tablet, I blame all wrong words in Swype
Do your parents or siblings have HBO? If they do and they'll give you their log in info for their cable provider, you can get all the past seasons on HBO Go.