Any two numbers that you choose can be the next number. It is easy to find a rule based on a polynomial of order 6 such that the first five numbers are as listed in the question followed by the chosen next two numbers. 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 rule for the given numbers, based on a polynomial of order 4, is
t(n) = (5n^4 - 58n^3 + 235n^2 - 380n + 213)/3 for n = 1, 2, 3, ...
and, accordingly, the next two numbers in the sequence are 115 and 393.
But it would be easy to find a rule so that the next two were 4 and 6, for example.
-17, -21 Pattern is subtract 4.
13 21 34 55
The next number in the sequence 3-15-6-30-21 is -207.
1, 1, 2, 3, 5, 8, 13, 21, ...Restate the question: What are the terms of the Fibonacci sequence?The Fibonacci sequence is formed by beginning with the first two terms both equal to one. From there on, each term is found by adding the two previous terms:1+1=2, 1+2=3, 2+3=5, 3+5=8, 5+8=13, 8+13=21, ...
A Fibonacci sequence is a mathematical sequence that starts with zero, and continues by adding the previous two terms. The Fibonacci sequence starts: 0, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55. Each term from the second term onwards is achieved by adding the pervious two terms.
The Fibonacci sequence is infinite. The next two terms are 89 and 144.
1 5 9 13 17 21
-17, -21 Pattern is subtract 4.
This is called the Fibonacci sequence. The last two numbers in the sequence are added together to produce the next. Therefore, following 8 and 13 are: 8 + 13 = 21 13 + 21 = 34 21 + 34 = 55 34 + 55 = 89 55 + 89 = 144
The next three numbers in the sequence are 23, 25, and 27.
13 21 34 55
Since the terms of the given sequence differ by different numbers, then the terms would start a new pattern, so that the other term of the sequence is 23.16 26 21 13 23 18 10...
This is a Fibonacci sequence with alternate terms omitted. The first two numbers in the Fibonacci sequence are 0 and 1, and each subsequent number is the sum of the previous two. (0),1,(1),2,(3),5,(8),13,(21),34,(55),89 The bracketed terms are the omitted terms. The next number would thus be 89
13, 21 - it is the Fibonacci sequence
The next two numbers in the sequence are... 45 & 54.
The next number in the sequence 3-15-6-30-21 is -207.
The next number in this sequence is 13112221.