Answer:
[tex]d_{n+1}=d_n\,+\,2^n[/tex]
with [tex]d_1=81[/tex]
Step-by-step explanation:
We can study what happens day by day starting with day one (1) to understand how the recursive relation can be constructed:
Day # Number of stamps What is added relative to previous day
1 d1 = 80 + 1 = 81
2 d2 = 81 + 2 = 83 d2 = d1 + 2
3 d3 = 83 + 4 = 87 d3 = d2 + [tex]2^2[/tex]
4 d4 = 87 + 8 = 95 d4 = d3 + [tex]2^3[/tex]
5 d5 = 95 + 16 = 111 d5 = d4 + [tex]2^4[/tex]
6 d6 = 111 + 32 = 143 d6 = d5 + [tex]2^2[/tex]
(n+1) d(n+1) = dn + [tex]2^n[/tex]