86, 116, 153, ...
(86+30=116, 116+37=153. pattern continues like this with the number being added increasing by 7 each time.)
find the 30th term
Your sequence should continue like this:
86, 116, 153, 197, 248, 306, 371, 443, 522, 608, 701, 801, 908, 1022, 1143, 1271, ...etc.
The "closed form" of the sequence is:
a(n)= 1/2 (7 n^2 + 39 n + 126) (for any term)
a(30) ==1/2 * (7*30^2 + 39*30 + 126)
a(30) ==3,798
