in Q (25 characters)

t:{(x-1) (p:{0+':x,0})\1}

Sample usage:

q)t 4
1
1 1
1 2 1
1 3 3 1

in Q (25 characters/20 with shorter version)

t:{(x-1) (p:{0+':x,0})\1}

Shorter

t:{(x-1){0+':x,0}\1}

Sample usage:

q)t 4
1
1 1
1 2 1
1 3 3 1