C
The sequence pattern appears to be alternating between a number and its corresponding letter in the alphabet. The numbers 1, 2, 3, 4 correspond to the letters A, B, C, D. Therefore, the next letter in the sequence would be E.
It is the sequence of first differences. If these are all the same (but not 0), then the original sequence is a linear arithmetic sequence. That is, a sequence whose nth term is of the form t(n) = an + b
18 b/c the pattern is +1,+2,+3...
T
d
The next letter in the sequence is S. The pattern follows the alphabet sequence with each letter moving forward two positions.
the next letter would be 'b'
B
f
c
i
I,V
CRC CBO and COL
d
m
b
c