y = 2.5*x^2 - 3.2*x + 1.6 is the equation.
So using that equation, 26 is the incorrect number in the pattern.
I plotted this in excel and fit a 2nd order polynomial trendline and tested to see what numbers worked.
20, 21, 22, 23, 24, 25, 26, 27, 28, 29
The "pairs" in the sequence are doubles of themselves, e.g (1,2) , (5, 10), (13, 26) but for 29 and 48 neither are doubles or halves of each other. However I'm not sure how you know which of 29 or 48 is the odd one out.
21
26
29 26 35 29 26 30 26 18 29 19 18 19 18 29 26 20 18 32 16 29 24 21 35 30 29 28 37 39 29 26.34 6.17
29
58
The missing number is 26. The number after 29 is 58.
29
20, 21, 22, 23, 24, 25, 26, 27, 28, 29
The "pairs" in the sequence are doubles of themselves, e.g (1,2) , (5, 10), (13, 26) but for 29 and 48 neither are doubles or halves of each other. However I'm not sure how you know which of 29 or 48 is the odd one out.
21
48 shoud be 58.
assuming it keeps the same pattern of +10 -5 alternating then the next number would be 26
29
26/29 ~= 89.66%
One possibility: -3