|
Search: id:A020653
|
|
|
| A020653 |
|
Denominators in canonical bijection from positive integers to positive rationals. |
|
+0
15
|
|
| 1, 2, 1, 3, 1, 4, 3, 2, 1, 5, 1, 6, 5, 4, 3, 2, 1, 7, 5, 3, 1, 8, 7, 5, 4, 2, 1, 9, 7, 3, 1, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 11, 7, 5, 1, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 13, 11, 9, 5, 3, 1, 14, 13, 11, 8, 7, 4, 2, 1, 15, 13, 11, 9, 7, 5, 3, 1, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 17
(list; graph; listen)
|
|
|
OFFSET
|
1,2
|
|
|
REFERENCES
|
Richard Courant and Herbert Robbins. What Is Mathematics?, Oxford, 1941, pp. 79-80.
H. Lauwerier, Fractals, Princeton Univ. Press, p. 23.
|
|
LINKS
|
David Wasserman, Table of n, a(n) for n = 1..100000
Index entries for "core" sequences
|
|
MAPLE
|
with (numtheory): A020653 := proc (n) local sum, j, k; sum := 0: k := 2: while (sum < n) do: sum := sum + phi(k): k := k + 1: od: sum := sum - phi(k-1): j := 1; while sum < n do: if gcd(j, k-1) = 1 then sum := sum + 1: fi: j := j+1: od: RETURN (k-j): end: # from UlrSchimke(AT)aol.com, Nov 06, 2001
|
|
CROSSREFS
|
Cf. A020652.
Sequence in context: A079786 A032451 A088445 this_sequence A094522 A118487 A091420
Adjacent sequences: A020650 A020651 A020652 this_sequence A020654 A020655 A020656
|
|
KEYWORD
|
nonn,frac,core,nice
|
|
AUTHOR
|
David W. Wilson (davidwwilson(AT)comcast.net)
|
|
|
Search completed in 0.002 seconds
|
