Yes. The calculation gets rather tedious, but the definition works for all positive integers.

It might be nice to have a Java method that does the calculation for us.
Here is a math-like definition of `Triangle(N)`

:

- Triangle( 1 ) = 1
- Triangle( N ) = N + Triangle( N-1 )

And here is a Java method that does this calculation:

int Triangle( int N ) { if ( N == 1 ) return 1; else return N + Triangle( N-1 ); }

The Java code is similar to the math-like definition of `Triangle()`

.
The `if`

statement has been added so that the base case is selected
when it is needed.