|
Search: id:A076648
|
|
|
| A076648 |
|
phi(n-1) + phi(n+1) = 1/2 sigma(n). |
|
+0
1
|
| |
|
|
OFFSET
|
1,1
|
|
|
EXAMPLE
|
phi(314) + phi(316) = 156 + 156 = 312 = 1/2 sigma(315), so 315 belongs to the sequence.
|
|
MATHEMATICA
|
Select[Range[2, 10^5], EulerPhi[ # - 1] + EulerPhi[ # + 1] == (1/2)DivisorSigma[1, # ] &]
|
|
CROSSREFS
|
Sequence in context: A050807 A157621 A104819 this_sequence A076773 A114807 A109130
Adjacent sequences: A076645 A076646 A076647 this_sequence A076649 A076650 A076651
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
Joseph L. Pe (joseph_l_pe(AT)hotmail.com), Oct 23 2002
|
|
|
Search completed in 0.002 seconds
|
