+865 https://web2.0calc.com/questions/i-need-some-help-with-this-other-problem
+23245 a1 = 1
a2 = 21·1 = 21
a3 = 22·2 = 23
a4 = 23·23 = 26
a5 = 24·26 = 210
a6 = 25·210 = 215
The exponents form the triangular numbers: 1, 3, 6, 10, 15, ...
The formula for the nth triangular number is n(n + 1)/2
This will give you the exponent upon 2 -- but be careful -- for a6, you want the 5th triangular number (etc).
