input：integers n, r, where 0<=r<=n
- results of P(n, r), with respect to n, r
- results of C(n, r), with respect to n, r
- results of n^r, with respect to n, r
- results of C(r+n-1, r), with respect to n, r
input：integers n, 0<=n
- results of the first n Catalan number, with respect to n
- results of the first n triangular number, with respect to n
- results of the first n harmonic number, with respect to n
- results of the first n Fibonacci number, with respect to n
- results of the first n Lucas number, with respect to n
For Example：
Catalan Number
input：6
output：1, 1, 2, 5, 14, 42
Harmonic Number
input：3
output：1, 3/2, 11/6
Lucas Number
input：8
output：2, 1, 3, 4, 7, 11, 18, 29
input：integers n, 0<=n
- results of Eulerian number, with respect to n
- results of Stirling number, with respect to n
For Example：
Eulerian number
input：4
output：1, 11, 11, 1
Stirling number
input：6
output：1, 31, 90, 65, 15, 1
WEBSITE： https://hungyennn.github.io/Combinatorial-Calculator/