Получить матрицу по правилу — QBasic(Бейсик)

1 2 3 ... 9 10
0 1 2 ... 8 9
0 0 1 ... 7 8
. . . ... . .
0 0 0 ... 0 1

CLS
n = 10
DIM a(n, n)
FOR i = 1 TO n
    c = 0
    FOR j = i TO n
        c = c + 1
        a(i, j) = c
    NEXT
NEXT
FOR i = 1 TO n
    FOR j = 1 TO n
        PRINT a(i, j);
    NEXT
    PRINT
NEXT