Often when given only a few numbers in a sequence or series, there is more than one possible answer.
As a sequence, this could be the numbers NOT divisible by 4. In this case the sequence is 1, 2, 3, 5, 6, 7, 9, 10, 11, 13, 14, 15, 17, 18, 19, 21, 22, 23, 25, 26, 27, 29, 30, 31, 33, 34, 35, 37, 38, 39, 41,...
The sequence could be: all numbers n such that 2n + 9 is prime, or it could be all numbers n such that 30(n)+13 is prime, just to name a few.
1650
the next one is 1234
All positive numbers come "after" 0 (or -0, if you prefer).
It seems that ecah number is obtained by squaring the previous number, then adding 2.
123
1650
124
It is 129.
I believe you meant an arithmetic series. It is a series of numbers differing by a certain number from the previous number of the series. In this case, they differ by 123.
123
402. The sequence alternates between multiply by 3, and add 11.
45
the next one is 1234
the anser is 123
129 The numbers are prime (don't consider the prefix 1)
All positive numbers come "after" 0 (or -0, if you prefer).
It is: (3*27)+42 = 123