Arithmetic

$a_n = a_1 + (n-1)d$

Geometric

$a_n = a_1 \cdot r^{(n-1)}$

Fibonacci

$F_n = F_{n-1} + F_{n-2}$

Prime

$P_n$ is the n-th prime number.

Powers of 2

$a_n = 2^{n-1}$

Factorial

$a_n = (n-1)!$

Triangular

$T_n = \frac{n(n+1)}{2}$

Square

$S_n = n^2$

Cube

$C_n = n^3$

Star

$St_n = 6n(n-1) + 1$

Harmonic

$H_n = \sum_{k=1}^{n} \frac{1}{k}$