login
This site is supported by donations to The OEIS Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A171263 Primes of the form 1 + 4-multiperfect numbers. 4
30241, 2178541, 23569921, 66433720321, 630532357710420079508428362350593, 1928622300236318049928258133164033, 651350717502447739281012140234441171379683329 (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))=4(x-1). See comment lines of the sequence A093034.

LINKS

Table of n, a(n) for n=1..7.

EXAMPLE

p=30241 is prime and sigma(p-1)/(p-1)=4, so p is in the sequence.

CROSSREFS

Cf. A027687, A093034, A171264, A171265.

Sequence in context: A323991 A109485 A156429 * A233731 A187376 A187373

Adjacent sequences:  A171260 A171261 A171262 * A171264 A171265 A171266

KEYWORD

fini,full,nonn

AUTHOR

M. F. Hasler and Farideh Firoozbakht, Apr 15 2010

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified March 18 16:00 EDT 2019. Contains 321292 sequences. (Running on oeis4.)