A070553 Rectangular array read by rows: n-th row gives the 7 numbers k*10^n mod 7 for 0 <= k < 7.

0, 1, 2, 3, 4, 5, 6, 0, 3, 6, 2, 5, 1, 4, 0, 2, 4, 6, 1, 3, 5, 0, 6, 5, 4, 3, 2, 1, 0, 4, 1, 5, 2, 6, 3, 0, 5, 3, 1, 6, 4, 2, 0, 1, 2, 3, 4, 5, 6, 0, 3, 6, 2, 5, 1, 4, 0, 2, 4, 6, 1, 3, 5, 0, 6, 5, 4, 3, 2, 1, 0, 4, 1, 5, 2, 6, 3, 0, 5, 3, 1, 6, 4, 2