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

1, 2, 5, 3, 7, 11, 4, 9, 14, 19, 5, 11, 17, 23, 29, 6, 13, 20, 27, 34, 41, 7, 15, 23, 31, 39, 47, 55, 8, 17, 26, 35, 44, 53, 62, 71, 9, 19, 29, 39, 49, 59, 69, 79, 89, 10, 21, 32, 43, 54, 65, 76, 87, 98, 109, 11, 23, 35, 47, 59, 71, 83, 95, 107, 119, 131

3

Triangle of one less than the conductor of a and b for the expression a*x + b*y. This is the greatest k such that a*x + b*y does not equal k for any 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) - 1, {n, 3, nn}, {m, 2, n - 1}]]

Cf. S000429 (one greater than these numbers), S000431, S000432 (three dimensional cases).

nonn,tabl

T. D. Noe, Dec 23 2014