Write the Word or Phrase That Best Completes Each Statement $a _ { 1 }$

Short Answer

Write the word or phrase that best completes each statement or answers the question.
Provide the missing information.
-Given an arithmetic sequence with first term $a _ { 1 }$ , and common difference d, the nth term is
represented by the formula $a _ { \mathrm { n } } =$ ________.