|
Search: id:A066168
|
|
|
| A066168 |
|
a(n) = least k such that EulerPhi(k) > sigma(n). |
|
+0
1
|
|
| 3, 5, 7, 11, 11, 17, 11, 17, 17, 23, 17, 31, 17, 29, 29, 37
(list; graph; listen)
|
|
|
OFFSET
|
1,1
|
|
|
COMMENT
|
Sigma dominates EulerPhi. Heuristically, a(n) = first time when EulerPhi overtakes sigma(n), if n is thought of as time. a(n) - n can be thought of as the "lag at time n" of EulerPhi behind sigma. 2. It is easily shown that all terms of a(n) are primes.
|
|
EXAMPLE
|
a(3) = 7 since EulerPhi(7) = 6 > sigma(3) = 4 and 7 is the first number to satisfy the inequality.
|
|
CROSSREFS
|
Sequence in context: A066066 A112070 A123252 this_sequence A109908 A102941 A114235
Adjacent sequences: A066165 A066166 A066167 this_sequence A066169 A066170 A066171
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
Joseph L. Pe (joseph_l_pe(AT)hotmail.com), Dec 13 2001
|
|
|
Search completed in 0.002 seconds
|
