A171264 Primes of the form 1 + 5-multiperfect numbers.

30823866178561, 796928461056001, 1802582780370364661761, 2827987212986831882236723201, 68688966922031309945174465761834751373920047004215278394826366933532673

Offset: 1

Author

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

Keywords

• fini
• full
• nonn

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))=5(x-1). See comment lines of the sequence A093034.

Examples

			p=30823866178561 is prime and sigma(p-1)/(p-1)=5, so p is in the sequence.
		

Crossrefs

Cf. A027687, A093034, A171263, A171265.