|
Search: id:A103176
|
|
|
| A103176 |
|
Prime with subscript=sigma(n), if p[sigma(n)]-p[phi(n)]=A067161(n)-A048848(n)=6, where p(j)=j-th prime. |
|
+0
1
|
|
| 3, 19, 43, 113, 463, 619, 863, 1789, 2273, 2383, 4519, 4789, 4937, 5443, 5507, 5653, 8237, 10459, 13007, 13697, 16063, 16453, 17389, 18313, 18919, 20903, 21193, 21319, 21383, 23567, 24109, 25309, 26267, 27947, 28283, 29573, 30559, 31183, 31517
(list; graph; listen)
|
|
|
OFFSET
|
1,1
|
|
|
COMMENT
|
Conjectured: In all cases sigma(n)-phi(n)=2, i.e. n is a prime number.
|
|
EXAMPLE
|
n=3719,sigma[n]=3720,phi(n)=3718, a(n)=p[sigma(n)]=34847.
|
|
MAPLE
|
Do[g=n; a=Prime[u=DivisorSigma[1, n]]; b=Prime[w=EulerPhi[n]]; s=a-b; If[Equal[s, 6], Print[{n, a, b, u, w, u-w}]; ta=Append[ta, a]], {n, 1, 10000}] ta=Delete[ta, 1]
|
|
CROSSREFS
|
Cf. A067161, A048848, A000020, A000203.
Sequence in context: A103145 A100694 A146664 this_sequence A028880 A162905 A063553
Adjacent sequences: A103173 A103174 A103175 this_sequence A103177 A103178 A103179
|
|
KEYWORD
|
nonn,uned
|
|
AUTHOR
|
Labos E. (labos(AT)ana.sote.hu), Mar 02 2005
|
|
|
Search completed in 0.006 seconds
|
