A076690 Nearest integer to average of the smallest and largest prime factors of n (0.5 is rounded to 1).

2, 3, 2, 5, 3, 7, 2, 3, 4, 11, 3, 13, 5, 4, 2, 17, 3, 19, 4, 5, 7, 23, 3, 5, 8, 3, 5, 29, 4, 31, 2, 7, 10, 6, 3, 37, 11, 8, 4, 41, 5, 43, 7, 4, 13, 47, 3, 7, 4, 10, 8, 53, 3, 8, 5, 11, 16, 59, 4, 61, 17, 5, 2, 9, 7, 67, 10, 13, 5, 71, 3, 73, 20, 4, 11, 9, 8, 79, 4, 3, 22, 83, 5, 11, 23, 16

Offset: 2

Author

Joseph L. Pe, Oct 25 2002

Keywords

• easy
• nonn

Examples

			The smallest and largest prime factors of 6 are 2 and 3, respectively, the average of which is 2.5, rounding off to 3. Hence a(6) = 3.
		

Programs

Mathematica

f[n_] := Module[{p, l}, p = Transpose[FactorInteger[n]][[1]]; l = Length[p]; Ceiling[(p[[1]] + p[[l]])/2]]; Table[f[i], {i, 2, 100}]