18 34 66
If 18 091 997 is a series of three separate numbers the roman numerals for them would be 18 = XVIII, 091 = XCI and 997 = CMXCVII.
30, 42, 38
-3 0 3 then 6 9 12 15 18 21 and so on ...
18, 27, 45
The pattern is add three and then multiply by three. The next number is 174.
18 34 66
A single number, such as 18233039, cannot define a series.
Well, judging by the sequence of numbers, the pattern would be to subtract one more than the last time from each new number. Meaning 33-1=32 then 32-2=30 then 30-3=27. The next three numbers would be 27-4=23 and 23-5=18 and finally 18-6=12. So 23 18 and 12 would be the next three numbers in sequence.
If 18 091 997 is a series of three separate numbers the roman numerals for them would be 18 = XVIII, 091 = XCI and 997 = CMXCVII.
30, 42, 38
-3 0 3 then 6 9 12 15 18 21 and so on ...
Based on the sample you have provided, I see that 4 numbers, counting by 2 from 12 to 18, form a repeating sequence. I would expect that the next 4 numbers in this series would again be 12, 14 16, and 18.
162 and 486 the pattern is that the next number is three times the previous number.
18
5+6+7=18
The sum of the prime numbers 2, 5, and 11 is 18.