A171263 Primes of the form 1 + 4-multiperfect numbers.

30241, 2178541, 23569921, 66433720321, 630532357710420079508428362350593, 1928622300236318049928258133164033, 651350717502447739281012140234441171379683329

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