|
Search: id:A071000
|
|
|
| A071000 |
|
Numbers n such that the denominator of sum(k=1,n,1/GCD(n,k)) equals n. |
|
+0
1
|
|
| 1, 2, 3, 4, 5, 7, 8, 9, 10, 11, 12, 13, 14, 16, 17, 19, 20, 22, 23, 24, 25, 26, 27, 28, 29, 31, 32, 34, 36, 37, 38, 39, 40, 41, 43, 46, 47, 49, 50, 52, 53, 55, 56, 57, 58, 59, 61, 62, 63, 64, 65, 67, 68, 71, 72, 73, 74, 75, 76, 77, 79, 80, 81, 82, 83, 85, 86, 88, 89, 91, 92, 93
(list; graph; listen)
|
|
|
OFFSET
|
1,2
|
|
|
COMMENT
|
Does lim n -> infinity a(n)/n = 3/2 ?
|
|
EXAMPLE
|
sum(k=1,12,1/GCD(12,k))=77/12 hence 12 is in the sequence.
|
|
PROGRAM
|
(PARI) for(n=1, 300, if(denominator(sum(i=1, n, 1/gcd(n, i))) == n, print1(n, ", ")))
|
|
CROSSREFS
|
Sequence in context: A052414 A095410 A022293 this_sequence A088451 A047595 A079298
Adjacent sequences: A070997 A070998 A070999 this_sequence A071001 A071002 A071003
|
|
KEYWORD
|
easy,nonn
|
|
AUTHOR
|
Benoit Cloitre (benoit7848c(AT)orange.fr), May 18 2002
|
|
|
Search completed in 0.002 seconds
|
