The triangle of nonzero (m - 1) * (n - 1) for 1 < m < n.

2, 3, 6, 4, 8, 12, 5, 10, 15, 20, 6, 12, 18, 24, 30, 7, 14, 21, 28, 35, 42, 8, 16, 24, 32, 40, 48, 56, 9, 18, 27, 36, 45, 54, 63, 72, 10, 20, 30, 40, 50, 60, 70, 80, 90, 11, 22, 33, 44, 55, 66, 77, 88, 99, 110, 12, 24, 36, 48, 60, 72, 84, 96, 108, 120, 132

3

Triangle of the conductor of a and b for the expression a*x + b*y. This is the least k such that a*x + b*y represents k and all greater integers for nonnegative x and y.

T. D. Noe, Plot of rows 3 to 100

T. D. Noe, Table of rows 3 to 100

David Bessoud and Stan Wagon, A Course in Computational Number Theory, Key College Publishing, 2000.

(Mma) nn = 15; Flatten[Table[(m - 1) (n - 1), {n, 3, nn}, {m, 2, n - 1}]]

Cf. S000430 (one less than these numbers), S000431, S000432 (three dimensional cases).

nonn,tabl

T. D. Noe, Dec 23 2014