login
The OEIS is supported by the many generous donors to the OEIS Foundation.
Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A171266
Primes of the form 1 + triperfect numbers.
1
673, 523777
(list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
COMMENTS
A subsequence of A093034.
If p is a term of this sequence then for each positive integer k, x=p^k
is a solution for the equation sigma(phi(x))=3(x-1). See comment lines of
the sequence A093034.
LINKS
Table of n, a(n) for n=1..2.
Achim Flammenkamp, The Multiply Perfect Numbers Page
EXAMPLE
p=673 is prime and sigma(p-1)/(p-1)=3, so p is in the sequence.
CROSSREFS
Cf. A005820, A093034, A171263, A171264, A171265.
Sequence in context: A335254 A160209 A234117 * A267818 A158392 A264328
Adjacent sequences: A171263 A171264 A171265 * A171267 A171268 A171269
KEYWORD
fini,full,nonn,bref
AUTHOR
M. F. Hasler and Farideh Firoozbakht, Apr 15 2010
STATUS
approved

Lookup Welcome Wiki Register Music Plot 2 Demos Index WebCam Contribute Format Style Sheet Transforms Superseeker Recents
The OEIS Community
Maintained by The OEIS Foundation Inc.
Last modified February 16 08:56 EST 2025. Contains 380893 sequences.
License Agreements, Terms of Use, Privacy Policy