Question 393978
Notice that each difference between two successive terms is 3, 4, 5, 6, ...


We can generate a recursive sequence {{{a[n] = a[n-1] + n + C}}} where C is constant. Part of this is a little guess and check...I have found that C = 2.


{{{a[n] = a[n-1] + n + 2}}}, {{{a[1] = 0}}}


We can check by substituting a_2, a_3, and so on.