A143613 - OEIS

A143613

Triangle read by rows: A051731 * A127368.

1, 2, 0, 2, 2, 0, 3, 0, 3, 0, 2, 2, 3, 4, 0, 4, 2, 0, 0, 5, 0, 2, 2, 3, 4, 5, 6, 0, 4, 0, 6, 0, 5, 0, 7, 0, 3, 4, 0, 4, 5, 0, 7, 8, 0, 4, 2, 6, 4, 0, 0, 7, 0, 9, 0, 2, 2, 3, 4, 5, 6, 7, 8, 9, 10, 0, 6, 2, 3, 0, 10, 0, 7, 0, 0, 0, 11, 0, 2, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 0

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OFFSET

1,2

COMMENTS

A051731 = the inverse Moebius transform.

A127368 records the reduced residue system mod n, by rows.

Left border = d(n).

Row sums = A057661: (1, 2, 4, 6, 11, 11, 22, 22, 31, ...).

LINKS

Table of n, a(n) for n=1..91.

EXAMPLE

First few rows of the triangle;