n=9:k=4
screen 2
window(0,0)-(k,n-k)
cls

sub ns(a(1))
shared n,k
call dd(a())
for i=k to 1 step -1
if a(i)<n-k+i then
a(i)=a(i)+1
for j=i+1 to k
a(j)=a(j-1)+1
next j
exit sub
end if
next i
end sub

dim a(k)
for i=1 to k
a(i)=i
next i

xx:
call ns(a())
while not instat
wend
if inkey$=chr$(13) then end
goto xx:

sub dd(a(1))
cls
pset(0,0)
shared k,n
local b(),x,y
dim b(n)
for i=1 to k
b(a(i))=1
next i
for j=1 to n
if b(j)=1 then x=x+1 else y=y+1
line -(x,y)
next j
end sub