|
| |
|
|
A126262
|
|
a(n) is the denominator of the sum of the reciprocals of the positive integers k, k<=n, where every positive integer <= k and coprime to k is also coprime to n.
|
|
1
| |
|
|
1, 2, 6, 4, 60, 3, 140, 24, 9, 20, 27720, 4, 360360, 84, 10, 560, 12252240, 36, 77597520, 10, 21, 1320, 118982864, 72, 50, 520, 7560, 42, 2329089562800, 15, 72201776446800, 1441440, 99, 9520, 420, 120, 485721041551200, 95760, 468, 24, 19914562703599200
(list; graph; refs; listen; history; internal format)
|
|
|
|
OFFSET
| 1,2
|
|
|
EXAMPLE
| The positive integers k, k <= 6, where every positive integer <=k and coprime to k is also coprime to 6, are 1,2,6. So a(6) = 3 is the denominator of 1 +1/2 +1/6 = 5/3.
|
|
|
MATHEMATICA
| f[n_] := Select[Range[n], GCD[ #, n] == 1 &]; g[n_] := Plus @@ (1/# &) /@ Select[Range[n], Times @@ GCD[f[ # ], n] == 1 &]; Table[Denominator[g[n]], {n, 41}] (*Chandler*)
|
|
|
CROSSREFS
| Cf. A126260, A126261.
Sequence in context: A181822 A174940 A108435 * A080499 A072513 A022404
Adjacent sequences: A126259 A126260 A126261 * A126263 A126264 A126265
|
|
|
KEYWORD
| frac,nonn
|
|
|
AUTHOR
| Leroy Quet Dec 22 2006
|
|
|
EXTENSIONS
| Extended by Ray Chandler (rayjchandler(AT)sbcglobal.net), Dec 24 2006
|
| |
|
|
