|
Search: id:A066111
|
|
|
| A066111 |
|
Prime powers m such that Sigma4[m^2]/Sigma2[m^2] is a prime. |
|
+0
4
|
|
| 2, 3, 5, 13, 17, 31, 43, 61, 83, 109, 121, 125, 131, 229, 239, 257, 263, 269, 311, 313, 343, 361, 443, 463, 503, 571, 593, 599, 619, 641, 647, 653, 659, 701, 797, 811, 853, 953, 967, 1009, 1031, 1039, 1063, 1123, 1373, 1459, 1483, 1499, 1663, 1669, 1693
(list; graph; listen)
|
|
|
OFFSET
|
1,1
|
|
|
COMMENT
|
m=(p^w) such that A001159[m^2]/A001157[m^2] is prime, i.e. m^2 is in A066109.
Also m is square root of a term from A066109 (omitting the term 20). Apart from 20, up to 10000000 A066109 consists of squares of prime powers.
|
|
EXAMPLE
|
m=125: m^2=15625=A066109[13], Sigma4[15625]=59700165039453751, Sigma2[15625]=254313151, Sigma4/Sigma2=234750601=A066110[13] is prime. Observe also that Sigma2 is close to Sigma4/Sigma2.
|
|
CROSSREFS
|
Cf. A001159, A001157, A066109, A066110.
Adjacent sequences: A066108 A066109 A066110 this_sequence A066112 A066113 A066114
Sequence in context: A140558 A140549 A105879 this_sequence A065820 A108562 A087523
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
Labos E. (labos(AT)ana.sote.hu), Dec 06 2001
|
|
|
Search completed in 0.002 seconds
|
