Dou:=proc(C,n) local C1,i:
C1:=[seq(C[i] union {n},i=1..nops(C))]:
if nops(C)>1 then
[op(C),C1[nops(C1)]],[op(1..nops(C1)-1,C1)]:
else
 :
[op(C),C1[nops(C1)]]:
fi
end:

Scd:=proc(n) local S:

if n=0 then
   RETURN([[{}]]):
fi:

S:=Scd(n-1):
[seq(Dou(S[i],n),i=1..nops(S))]:

end: