

A171263


Primes of the form 1 + 4multiperfect numbers.


4




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(x1). See comment lines of the sequence A093034.


LINKS

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


EXAMPLE

p=30241 is prime and sigma(p1)/(p1)=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



