OFFSET
1,1
COMMENTS
Radicals of even perfect numbers. - Charles R Greathouse IV, Feb 01 2013
LINKS
Amiram Eldar, Table of n, a(n) for n = 1..18
Florian Luca and Carl Pomerance, On the radical of a perfect number, New York Journal of Math., 16 (2010), 23-30; alternative link.
FORMULA
MATHEMATICA
2*(2^MersennePrimeExponent[Range[15]]-1) (* Harvey P. Dale, Jan 05 2020 *)
PROG
(PARI) apply(p->2*(2^p-1), select(p->ispseudoprime(2^p-1), primes(40))) \\ Charles R Greathouse IV, Feb 01 2013
CROSSREFS
KEYWORD
nonn
AUTHOR
Omar E. Pol, Apr 23 2008
EXTENSIONS
Corrected and extended by Joerg Arndt, Jun 07 2012.
STATUS
approved