|
Search: id:A071114
|
|
|
| A071114 |
|
Numbers n such that n and sigma(n) are prime powers (of the form p^k, p prime, k>=1). |
|
+0
1
|
|
| 2, 3, 4, 7, 9, 16, 25, 31, 64, 81, 127, 289, 729, 1681, 2401, 3481, 4096, 5041, 7921, 8191, 10201, 15625, 17161, 27889, 28561, 29929, 65536, 83521, 85849, 131071, 146689, 262144, 279841, 458329, 491401, 524287, 531441, 552049, 579121, 597529
(list; graph; listen)
|
|
|
OFFSET
|
1,1
|
|
|
MATHEMATICA
|
Select[ Range[10^6], f[ # ] == f[ DivisorSigma[1, # ]] == 1 & ]
|
|
PROGRAM
|
(PARI) for(n=1, 100000, if(omega(n)*omega(sigma(n)) == 1, print1(n, ", ")))
|
|
CROSSREFS
|
Sequence in context: A027947 A067236 A070763 this_sequence A078696 A098115 A082673
Adjacent sequences: A071111 A071112 A071113 this_sequence A071115 A071116 A071117
|
|
KEYWORD
|
easy,nonn
|
|
AUTHOR
|
Benoit Cloitre (benoit7848c(AT)orange.fr), May 27 2002
|
|
EXTENSIONS
|
Edited by Robert G. Wilson v (rgwv(AT)rgwv.com) and David Wasserman (wasserma(AT)spawar.navy.mil), May 30 2002
|
|
|
Search completed in 0.004 seconds
|
