The word appears 204 times.
The word nigger is used throughout Hick Finn. It has no negative connotation - well - not in and of itself. It was the common word for the black race at the time. Any negative connotation comes from the attachment of stereotypes to the race and not just to the word. The following is typical...
There are too many examples to list them all, but here is a typical paragraph from the book:
"As soon as Tom was back we cut along the path, around the garden fence, and by and by fetched up on the steep top of the hill the other side of the house. Tom said he slipped Jim's hat off of his head and hung it on a limb right over him, and Jim stirred a little, but he didn't wake. Afterward Jim said the witches bewitched him and put him in a trance, and rode him all over the State, and then set him under the trees again, and hung his hat on a limb to show who done it. And next time Jim told it he said they rode him down to New Orleans; and, after that, every time he told it he spread it more and more, till by and by he said they rode him all over the world, and tired him most to death, and his back was all over saddle-boils. Jim was monstrous proud about it, and he got so he wouldn't hardly notice the other niggers.Niggers would come miles to hear Jim tell about it, and he was more looked up to than any nigger in that country. Strange niggers would stand with their mouths open and look him all over, same as if he was a wonder. Niggers is always talking about witches in the dark by the kitchen fire; but whenever one was talking and letting on to know all about such things, Jim would happen in and say, "Hm! What you know 'bout witches?" and that nigger was corked up and had to take a back seat. Jim always kept that five-center piece round his neck with a string, and said it was a charm the devil give to him with his own hands, and told him he could cure anybody with it and fetch witches whenever he wanted to just by saying something to it; but he never told what it was he said to it. Niggers would come from all around there and give Jim anything they had, just for a sight of that fivecenter piece; but they wouldn't touch it, because the devil had had his hands on it. Jim was most ruined for a servant, because he got stuck up on account of having seen the devil and been rode by witches. "