|
Search: id:A107439
|
|
|
| A107439 |
|
a(1)=2, a(n) is the smallest prime > a(n-1) so that a(n) is a primitive root mod a(n-1) and vice versa. |
|
+0
1
|
|
| 2, 3, 5, 7, 17, 23, 89, 113, 137, 149, 163, 181, 191, 233, 257, 263, 277, 283, 397, 419, 421, 443, 449, 461, 463, 509, 557, 569, 593, 599, 613, 619, 701, 719, 821, 823, 829, 857, 863, 877, 919, 1097, 1103, 1117, 1171, 1181, 1193, 1213, 1237, 1259, 1361, 1367
(list; graph; listen)
|
|
|
OFFSET
|
1,1
|
|
|
COMMENT
|
if a(n) is 3 mod 4, then by quadratic reciprocity, if q is 3 mod 4, then either q is a square mod a(n) or vice versa, so a(n+1) must be 1 mod 4.
|
|
EXAMPLE
|
a(5)=17 because 7 is a primitive root mod 17, and 17 (=3 mod 7) is a primitive root mod 7. Also a(5) is not 11 since 11 has order 3 mod 7, a(5) is not 13 since 13 has order 2 mod 7
|
|
CROSSREFS
|
Adjacent sequences: A107436 A107437 A107438 this_sequence A107440 A107441 A107442
Sequence in context: A066277 A135948 A060212 this_sequence A030480 A048418 A074788
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
John L. Drost (drost(AT)marshall.edu), May 26 2005
|
|
|
Search completed in 0.002 seconds
|
