A104608 Write the natural numbers in base 4 in a triangle with k digits in the k-th row, as shown below. Sequence gives the leading diagonal.

1, 3, 1, 1, 1, 0, 1, 2, 1, 1, 0, 0, 2, 1, 2, 3, 1, 3, 1, 2, 2, 1, 1, 1, 2, 0, 0, 2, 1, 0, 2, 2, 2, 1, 0, 2, 0, 0, 3, 3, 2, 2, 0, 1, 1, 0, 1, 0, 1, 1, 1, 1, 1, 1, 1, 2, 3, 2, 1, 1, 2, 2, 3, 1, 1, 3, 2, 0, 2, 2, 1, 0, 1, 2, 2, 2, 3, 2, 2, 2, 3, 3, 3, 3, 3, 0, 0, 1, 3, 3, 2, 2, 2, 3, 3, 3, 2, 3, 0, 1, 1, 2, 1, 1, 2