41

2.5 and 3. In the top sequence the numbers progress × 1.5. In the bottom sequence the numbers progress × 2.5.

34826: each number is the sum of the last two digits of the previous number, preceded by the remaining numbers in reverse.

303
because if we put together the numbers: 21-22-23-24-25-26-27-28-29 and the next are 30 and 31

353
(x*2-1)

60.
100 years in a century, 365 days in a year, 24 hours in a day, 60 minutes in an hour, & 60 seconds in a minute.

677

74
(x-7, -6, -5, -4, -3)

10, 2 (two series – every second number: 7, 8, 9, 10 and 5, 4, 3, 2)

29
(a+b=c, b+c=d, c+d=e …)

54, 58
(x*2, +1, *2, +2, *2, +3, *2, +4)

48
(x+5, +7, +9, +11, +13)