It is possible to produce a formula so that any number of your choice could be the next number. Using Occam's razor though, the simplest answer is 54.
53 928
52 Saturdays and 53 Sundays.52 Saturdays and 53 Sundays.52 Saturdays and 53 Sundays.52 Saturdays and 53 Sundays.52 Saturdays and 53 Sundays.52 Saturdays and 53 Sundays.52 Saturdays and 53 Sundays.52 Saturdays and 53 Sundays.52 Saturdays and 53 Sundays.52 Saturdays and 53 Sundays.52 Saturdays and 53 Sundays.
212.
There were 53 Sundays and 52 Saturdays in 2012.There were 53 Sundays and 52 Saturdays in 2012.There were 53 Sundays and 52 Saturdays in 2012.There were 53 Sundays and 52 Saturdays in 2012.There were 53 Sundays and 52 Saturdays in 2012.There were 53 Sundays and 52 Saturdays in 2012.There were 53 Sundays and 52 Saturdays in 2012.There were 53 Sundays and 52 Saturdays in 2012.There were 53 Sundays and 52 Saturdays in 2012.There were 53 Sundays and 52 Saturdays in 2012.There were 53 Sundays and 52 Saturdays in 2012.
240
The next number would be 212, because the pattern is add 1 (2->3) and times by 4 (3x4=12)... so 52 add 1 = 53, so 53 x 4 =212.
212
-52 + (-53) = -105
10. Every year is longer than 52 weeks and so there is a week 53 in every year.
107
212 plus 1, times 4
The pattern is: n = n + 1 n = n * 4 repeat So, 2, 3, 12, 13, 52, 53, 112, 113, 452, 453, ...