Enter two numbers to generate a regular sequence

How to generate the following series:

(A means the largest number in the sequence, D means the length of the result sequence. Please see the example below for specific rules)

A=4, D=2:

The result is [1 2],[1 3],[1 4],[2 3],[2 4],[3 4].

A=6, D=2:

The result is [1 2],[1 3],[1 4],[1 5],[1 6],[2 3],[2 4],[2 5],[2 6],[3 4],[3 5],[3 6],[4 5],[4 6],[5 6].

A=5, D=3:

The result is [1 2 3],[1 2 4],[1 2 5],[1 3 4],[1 3 5],[1 4 5],[2 3 4],[2 3 5] ,[2 4 5],[3 4 5].

A and D are input values.

Answer 1

[Arthur Roué]

nchoosek(1:A, D)

Here a link to nchoosek documentation.