Any number that you choose can be the 15th number. It is easy to find a rule based on a polynomial of order 4 such that the first four numbers are as listed in the question followed by the chosen number as the 15th term. There are also non-polynomial solutions. Short of reading the mind of the person who posed the question, there is no way of determining which of the infinitely many solutions is the "correct" one.
One possible solution is to use the following polynomial of order 3 for the first 4 numbers:
U(n) = (-32*n^3 + 228*n^2 - 478*n + 291)/3 for n = 1, 2, 3, ...
so that U(15) = -21193
every next term is 4 smaller than previous so 7th term = -23
after -9 it is -15 then -21, -27 and the ninth is -36
Double it minus the previous number.
To find the common ration in a geometric sequence, divide one term by its preceding term: r = -18 ÷ 6 = -3 r = 54 ÷ -18 = -3 r = -162 ÷ 54 = -3
It is U(n) = 15*3^(n-1) = 5*3^n for n = 1, 2, 3, ...
every next term is 4 smaller than previous so 7th term = -23
To find the equation of a sequence, you first have to look at the differences between the numbers. In this case the differences are 4, and 4. Thus the equation begins 4n. The sequence minus 4n is: 3, 3, 3 Thus the equation in its entirety is that the value of the term in position n is 4n+3
The nth term in this sequence is 4n + 3.
Well, honey, the nth term for that sequence is n^2 + 2. Just plug in the value of n and you'll get your next number in the sequence. Keep it simple, darlin'.
It is: -3072
It is: -3072
after -9 it is -15 then -21, -27 and the ninth is -36
15 since you multiply by 3 then subtract 3 in sequence
9
The nth term is 4n-1 and so the next term will be 19
According to Wittgenstein's Finite Rule Paradox every finite sequence of numbers can be a described in infinitely many ways and so can be continued any of these ways - some simple, some complicated but all equally valid. Conversely, it is possible to find a rule such that any number of your choice can be the next one.The simplest rule is un = 18 - 3n
Double it minus the previous number.