From the recursive formula:
![a_n=a_(n-1)-\pi](https://img.qammunity.org/2023/formulas/mathematics/college/5lue5967vxkaory5tgsfzsd0uqv0q8u2lj.png)
we notice that the common difference of the sequence is -pi. Now we know that the first term is 7, then the explicit formula is:
![a_n=7-\pi(n-1)](https://img.qammunity.org/2023/formulas/mathematics/college/x9szgnqkwdiytnz69ckoruimbspx8g4hdu.png)
when
![n>0](https://img.qammunity.org/2023/formulas/mathematics/college/k51njip3kj1f3lyuu91qtefp9ywwdscdiq.png)
We can relabel this sequence if we assume we start at zero, in this case the sequence will be:
![a_n=7-\pi n](https://img.qammunity.org/2023/formulas/mathematics/college/rgh8iuab58holxee0jars22ri02cfaa5lk.png)
when:
![n\ge0](https://img.qammunity.org/2023/formulas/mathematics/college/e7pnq3pe0kcdzq2y727t6lr13x6nkcymnq.png)