The 13 should be 31... then 1+1+1=3 1+1+3=5 1+3+5=9...
18. The pattern is add 5, then subtract 1.
1 5 9 13 17 21
+5
There are 10 possible combinations so 60 possible permutations. The combinations are:(1, 3, 21), (1, 5, 19), (1, 7, 17), (1, 9, 15), (1, 11, 13),(3, 5, 17), (3, 7, 15), (3, 9, 13), (5, 7, 13), (5, 9, 11).
The 13 should be 31... then 1+1+1=3 1+1+3=5 1+3+5=9...
18. The pattern is add 5, then subtract 1.
18. The pattern is 3+1=4, 4+2=6, 6+3=9, 9+4=13, so 13+5=18
Use a text-editor.
13 - 5 + 112 = 9
1 5 9 13 17 21
13...... 9 plus 5 equals 14...... 14 minus 1 equals 13
1, 5, 2, 6, 3, 7, 4, 8, 5, 9, 6, 10, 7, 11, 8, 12, 9, 13, etc.
1, 5, 9, 13....
The rule for this sequence appears to be adding consecutive prime numbers. The sequence starts with 3, then adds the next prime number 2 to get 4. It then adds 3 (the next prime number) to 4 to get 7, then 5 to 7 to get 12, and so on. Each number in the sequence is the sum of the previous number and the next prime number in order.
To find the pattern, simply look for the difference in the first two numbers, then the following pair of numbers, etc. 2 9 5 13 10 19 17 2 + 7 = 9 9 - 4 = 5 5 + 8 = 13 13 - 3 = 10 10 + 9 = 19 19 - 2 = 17 The pattern is +7, -4, +8, -3, +9, -2...
9 1/16. (1 times 5 is 5, and 13/16 times 5 is 65/16 which is 4 1/16; the 4 adds to the 5 to give 9, and then the 1/16 makes it 9 1/16.)