vim : occupied from tmux/screen

Question

I use screen/tmux and vim.
In vim, I can't use <c-a> for increment a number, <c-a> is occupied from screen/tmux.

any suggestion for a simple map for increment a number ?

I try with

nnoremap <c-A> <c-a>

but, with this I have push down two times <c-A>

<c-A><c-A>

and with <c-X> never decrement the number

Answer 1

With screen, i've no problem. For doing a Control-a you have to do : C-a a

$ screen
$ vim foobar

type 'i' for insertion mode
type '1' 
type 'ESC'
type C-a a

=> 1 becomes 2

Hope this helps.

Answer 2

This question will probably help out. To repeat my answer from there, I prefer C-] as the tmux / screen key, because it doesn't get in the way of normal bindings in either vim or emacs.