you can use the casio calculator to solve pattern questions actually! they’ll teach you in upper sec but anyway it’s mode 3:2 on the calculator. then key in 1, 1, 1, first term of sequence followed by 4, 2, 1, second term of sequence then lastly 9, 3, 1, third term of sequence. they’ll give you three values, namely X, Y and Z. then you just have to input the numbers into the formula Tn= Xn² + Yn + Z
good luck!