Respuesta :
This pattern looks complicated so it could be anything. One possible pattern is
a(n) = ( 21·5ⁿ - 25 ) / 20
So pattern starts at n=1 and sequence would be 4, 25, 130, 655, 3280, ...
a(n) = ( 21·5ⁿ - 25 ) / 20
So pattern starts at n=1 and sequence would be 4, 25, 130, 655, 3280, ...