table: [['district', 'vacator', 'reason for change', 'successor', 'date successor seated'], ['missouri 5th', 'john g miller ( o )', 'died may 11 , 1856', 'thomas p akers ( kn )', 'seated august 18 , 1856'], ['virginia 1st', 'thomas h bayly ( d )', 'died june 23 , 1856', 'muscoe r h garnett ( d )', 'seated december 1 , 1856'], ['new mexico territory at - large', 'josã m gallegos ( d )', 'contested election july 23 , 1856', 'miguel a otero ( d )', 'seated july 23 , 1856'], ['vermont 1st', 'james meacham ( o )', 'died august 23 , 1856', 'george t hodges ( r )', 'seated december 1 , 1856'], ['illinois 5th', 'william a richardson ( d )', 'resigned august 25 , 1856', 'jacob c davis ( d )', 'seated november 4 , 1856'], ['south carolina 4th', 'preston brooks ( d )', 'died january 28 , 1857', 'vacant', 'not filled this term'], ['new york 20th', 'orsamus b matteson ( o )', 'resigned february 27 , 1857', 'vacant', 'not filled this term'], ['new york 23rd', 'william a gilbert ( o )', 'resigned february 27 , 1857', 'vacant', 'not filled this term']]
ref: on 3 occasion , a Successor was not named and those seat remained Vacant
template: on 3 occasion , a [ENT] was not named and those seat remained [ENT]