Respuesta :

Each number is mutliplied by 3 and then numbers 2,3,4,5,... are added successively.

2*3+2=8

8*3+3=27

27*3+4=85

85*3+5=260

260*3+6=786

So it's 786.

Btw, the general formula for this sequence is [tex] a_n=\dfrac{1}{12}(-6n+13\cdot3^n-9) [/tex]