go to this website for help
https://www.google.com/search?q=what+is+the+volume+of+a+triangular+prism&rlz=1C5CHFA_enUS801US801&oq=wha+is+the+volume+of+a+tria&aqs=chrome.1.69i57j0j69i60j0l3.6959j0j7&sourceid=chrome&ie=UTF-8
Would assume this to be: n² + 50
First term, n=1, n² + 50 = 1² + 50 = 1*1 + 50 = 1 + 50 = 51
Second term, n=2, n² + 50 = 2² + 50 = 2*2 + 50 = 4 + 50 = 54
Third term, n=3, n² + 50 = 3² + 50 = 3*3 + 50 = 9 + 50 = 59
First three terms are: 51, 54, & 59.