|
Search: id:A065148
|
|
|
| A065148 |
|
Phi[m]*Sigma[m] is divisible by m+1. |
|
+0
1
|
|
| 15, 20, 35, 95, 104, 143, 207, 255, 287, 319, 323, 464, 539, 650, 890, 899, 1023, 1034, 1199, 1295, 1349, 1407, 1519, 1763, 1952, 2015, 2204, 2834, 2975, 3599, 4031, 4454, 4607, 5183, 6479, 9215, 9503, 9799, 10403, 11339, 11663, 12095, 12824, 13055
(list; graph; listen)
|
|
|
OFFSET
|
0,1
|
|
|
FORMULA
|
Mod[A000010[m]*A000203[m], m+1]=0, m is composite.
|
|
EXAMPLE
|
m=95, Phi[95]=72, Sigma[95]=120, product=8640, quotient=90; for primes the formula holds.
|
|
MATHEMATICA
|
Do[s=EulerPhi[n]*DivisorSigma[1, n]; If[IntegerQ[s/(n+1)]&&!PrimeQ[n], Print[n]], {n, 1, 100000}]
|
|
CROSSREFS
|
A000010, A000203, A062354, A011257.
Sequence in context: A111200 A088494 A109659 this_sequence A093028 A105506 A120625
Adjacent sequences: A065145 A065146 A065147 this_sequence A065149 A065150 A065151
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
Labos E. (labos(AT)ana.sote.hu), Oct 18 2001
|
|
|
Search completed in 0.002 seconds
|
