|
Search: id:A128331
|
|
|
| A128331 |
|
a(1)=1. a(n) = number of positive numbers <= n that are coprime to a(n-1). |
|
+0
1
|
|
| 1, 2, 2, 2, 3, 4, 4, 4, 5, 8, 6, 4, 7, 12, 5, 13, 16, 9, 13, 19, 20, 9, 16, 12, 9, 18, 9, 19, 28, 13, 29, 31, 32, 17, 33, 22, 17, 36, 13, 37, 40, 17, 41, 43, 44, 21, 28, 21, 28, 21, 29, 51, 34, 25, 44, 25, 46, 28, 26, 28, 27, 42, 18, 21, 38, 31, 65, 51, 43, 69, 46, 34, 35, 52, 35
(list; graph; listen)
|
|
|
OFFSET
|
1,2
|
|
|
LINKS
|
Leroy Quet, Home Page (listed in lieu of email address)
|
|
EXAMPLE
|
a(6) = 4. The number of positive integers <= 7 that are coprime to 4 is four, these integers being 1, 3, 5 and 7. So a(7) = 4.
|
|
MATHEMATICA
|
a = {1}; For[n = 2, n < 80, n++, in = 1; co = 0; While[in < n + 1, If[GCD[a[[ -1]], in] == 1, co++ ]; in++ ]; AppendTo[a, co]]; a - Stefan Steinerberger (stefan.steinerberger(AT)gmail.com), May 29 2007
|
|
CROSSREFS
|
Sequence in context: A112176 A112205 A117953 this_sequence A084827 A029076 A036015
Adjacent sequences: A128328 A128329 A128330 this_sequence A128332 A128333 A128334
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
Leroy Quet May 04 2007
|
|
EXTENSIONS
|
More terms from Stefan Steinerberger (stefan.steinerberger(AT)gmail.com), May 29 2007
|
|
|
Search completed in 0.002 seconds
|
