" Select text linewise and you can use following command
" for sequencial numbering (in Japanese called rengbang).

" Sequencial numbering use default settings(ref. global variables).
:'<,'>RengBang
" Specify pattern like this. This sample is for array index.
:'<,'>RengBang \[\zs\(\d\+\)\ze\]
" Start sequencial numbering from 3.
:'<,'>RengBang \(\d\+\)  3
" Start from 3 and 2 step.
:'<,'>RengBang \(\d\+\)  0  2
" Start position use first detected number.
:'<,'>RengBang \(\d\+\)  0  1  1
" Use format %03d for replacing to sequencial number like '001.'.
:'<,'>RengBang \(\d\+\)  0  1  0  %03d.
" Use option same as above
:'<,'>RengBang --pattern=\(\d\+\) --start-number=0 --step-count=1 --format=%03d.
" You can specify both argument and options
:'<,'>RengBang \(\d\+\) 0 --format=%03d. --use-first

" You can use previous command options.
:'<,'>RengBangUsePrev
" Use previous pattern and set other options.
:'<,'>RengBangUsePrev  0  1  0  %d

" You can use function same as commands, all parameter is option.
" This is function's format.
"   rengbang#rengbang([pattern, start, step, usefirst, format])
"   rengbang#rengbang_use_prev([start, step, usefirst, format])
"   rengbang#rengbang_confirm()

" This is like :'<,'>RengBang \(\d\+\)  0  1  1  %d
:'<,'>call rengbang#rengbang('\(\d\+\)', 0, 1, 1, '%d')
" This is like :'<,'>RengBangUsePrev  1  1  0  %d
:'<,'>call rengbang#rengbang_use_prev(1, 1, 0, '%d')
" This is like :'<,'>RengBangConfirm
:'<,'>call rengbang#rengbang_confirm()

" You can use this function for customizing default settings.
" This is functions format
"   rengbang#config([pattern, start, step, usefirst, format])

" This is only config settings without sequencial numbering.
:call rengbang#config('\(\d\+\)', 0, 1, 1, '%d')

" If you want to customize default settings,
" you can change following gloval variable.

" Following settings is default value.
let g:rengbang_default_pattern  = '\(\d\+\)'
let g:rengbang_default_start    = 0
let g:rengbang_default_step     = 1
let g:rengbang_default_usefirst = 0
let g:rengbang_default_confirm_sequence = [
  \ 'pattern',
  \ 'start',
  \ 'step',
  \ 'usefirst',
  \ 'format',
  \ ]

" You can use following operator.

" This operator like :'<,'>RengBang (use default options).
map <Leader>sr <Plug>(operator-rengbang)
" This operator like :'<,'>RengBangUsePrev (use previous options).
map <Leader>sp <Plug>(operator-rengbang-useprev)