A164296 Let S(n) be the set of all positive integers that are <= n and are coprime to n. a(n) = the number of members of S(n) that are each coprime to every other member of S(n).
1, 1, 2, 2, 2, 2, 2, 4, 3, 2, 2, 4, 3, 4, 3, 4, 3, 6, 4, 6, 5, 4, 4, 8, 5, 5, 4, 6, 4, 8, 5, 8, 6, 6, 5, 8, 5, 7, 5, 7, 5, 10, 6, 9, 7, 8, 6, 12, 7, 10, 7, 9, 7, 13, 8, 10, 8, 8, 7, 14, 8, 10, 8, 11, 8, 13, 8, 12, 9, 11, 9, 15, 10, 12, 10, 13, 10, 16, 10, 14, 11, 13, 10, 18, 11, 14, 10, 14, 10, 20
Offset: 1
Keywords
Examples
The positive integers that are <= 9 and are coprime to 9 are: 1,2,4,5, 7,8. 1 is coprime to each other member in S(9). While 2, 4, and 8 are non-coprime to each other. 5 is coprime to each other member of S(9). And 7 is also coprime to each other member. Since there are 3 integers in S(9) that are coprime to each other member -- these integers being 1, 5, and 7 -- then a(9) = 3.
Links
- Reinhard Zumkeller, Table of n, a(n) for n = 1..1000
Programs
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Haskell
import Data.List ((\\)) a164296 n = length [m | let ts = a038566_row n, m <- ts, all ((== 1) . gcd m) (ts \\ [m])] -- Reinhard Zumkeller, May 28 2015
Extensions
Extended by Ray Chandler, Mar 16 2010
Comments