floyd_t(m):=block(
    t:m*(m+1)/2,
    L1:makelist(makelist(k,k,1,t),j,0,m),
    L2:makelist(rest(L1[i],((i-1)^2+(i-1))/2),i,1,m+1),
    makelist(firstn(L2[i],i),i,1,m),
    table_form(%%))$

/* Test cases */
floyd_t(5);
floyd_t(14);