Which of the following is not an indicator of sugarcane

What will come in place of the question mark (?) in the following series?

3.5, 9.5, 27.5, 81.5, 243.5, 729.5, ?

321,  240,  ?,  105,  51,  6

10      11       12        20       24       ?

4, 5, 11, 34, 137, ?

What will come in place of the question mark (?) in the following series?

100, 81, 64, 51, 40, ?

42, 48, 60, 84, 132, ?

What will come in place of the question mark (?) in the following series?

100, 729, 64, 343, 36, ?

64, 79, 109, 169, 289, ?

500, 400, 315, 245, ?, 150