Decorative header consisting of two groups of four black squares.

1. $a_1=3, b_n=4$ $\{a_n\}$
2. $a_1=2, b_n=2n$ $\{a_n\}$
3. $a_1=1, b_n=3n-2$ $\{a_n\}$
4. $a_1=5, b_n=n^2$ $\{a_n\}$
5. $a_1=2, b_n=2n^2+1$ $\{a_n\}$
6. $a_1=4, b_n=n^2+3n$ $\{a_n\}$
7. $a_1=1, b_n=2^{(n-1)}$ $\{a_n\}$
8. $a_1=3, b_n=3^n$ $\{a_n\}$
9. 1,2,5,10,17,26,... (i) $b_n$ (ii) $\{a_n\}$
10. 1,2,5,14,41,... (i) $b_n$ (ii) $\{a_n\}$