Summation Notation for a Linear Combination with a Break in the Index.

Question

I am trying to write a linear combination with an index running from 1 to 10, however, neglecting the index 5. I currently wrote the following: $$\sum_{i=1}^{4}c_{i}\phi _{i}+\sum_{i=6}^{10}c_{i}\phi _{i}$$ Is there a proper way to express this linear combination in a single sum, or is convention to keep it as expressed above (two sums)? My knowledge of notation for sums is limited, so I apologize if this is an easy question. Thank you for the help.

Answer 1

You can do something in the spirit of $$ \sum_{i=1, i\neq 5}^{10}\cdots $$ this is well defined. For me your notation is cleaner.