4. Describe the following patterns in your own words, and then extend each pattern by the sequence. \( \begin{array}{ll}\text { a) } 1 ; 3 ; 5 ; 7 ; 9 ; \ldots & \text { b) } 2 ; 1 ; 1 ; \frac{1}{4} \ldots \\ \text { c) } 6 ; 3 ; 0 ;-3 ;-6 ; \ldots & \text { d) } 1 ; 2 ; 4 ; 8 ; 16 ; \ldots \\ \text { e) } 4 ; 44 ; 484 ; 5324 ; \ldots & \text { f) } 1 ; 3 ; 6 ; 10 ; 15 ; \ldots \\ \text { 3. Study the pattern below and answer the questions that follow. }\end{array} \)

a) Odd numbers starting from 1, increasing by 2 each time. Extended sequence: 1; 3; 5; 7; 9; 11; 13; 15; 17; ... b) Starts with 2, followed by decreasing fractions of the previous term. Extended sequence: 2; 1; 1; 1/4; 1/16; 1/64; ... c) Starts at 6, decreasing by 3 each time. Extended sequence: 6; 3; 0; -3; -6; -9; -12; -15; ... d) Powers of 2, doubling each time. Extended sequence: 1; 2; 4; 8; 16; 32; 64; 128; ... e) Appending '4' to the end of the previous term. Extended sequence: 4; 44; 484; 5324; 53244; 532444; ... f) Triangular numbers, sum of first n natural numbers. Extended sequence: 1; 3; 6; 10; 15; 21; 28; 36; ...