References to A061857

Triangle where the k-th item at n-th row (both starting from 1) tells in how many ways we can add 2 distinct integers from 1 to n, in such way that the sum is divisible by k.
0, 1, 0, 3, 1, 1, 6, 2, 2, 1, 10, 4, 4, 2, 2, 15, 6, 5, 3, 3, 2, 21, 9, 7, 5, 4, 3, 3, 28, 12, 10

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