A sequence a1,a2,a3,… a_1, a_2, a_3, \dots\,a1,a2,a3,… is defined by
a1=1,a2=6an=an−1+an−2,n≥3 \begin{aligned}a_1 &= 1, a_2 = 6 \\a_n &= a_{n-1} + a_{n-2}, \quad n \geq 3\end{aligned} a1an=1,a2=6=an−1+an−2,n≥3Find a3,a4 a_3, a_4\,a3,a4 and a5a_5a5.
308 exam-style questions on AQA A Level Maths 1.7 D: Sequences and series, covering 1.7.1 Binomial expansion, 1.7.2 Types of sequence (A-level only), 1.7.3 Sigma notation (A-level only), 1.7.4 Arithmetic sequences and series (A-level only), 1.7.5 Geometric sequences and series (A-level only), and 1.7.6 Sequences and series in modelling (A-level only). Each one has a worked solution and a mark scheme showing where the marks go.